LeetCode

A collection of LeetCode questions to ace the coding interview! - Created using LeetHub v2

LeetCode Topics

String

0003-longest-substring-without-repeating-characters
0005-longest-palindromic-substring
0006-zigzag-conversion
0008-string-to-integer-atoi
0010-regular-expression-matching
0012-integer-to-roman
0013-roman-to-integer
0014-longest-common-prefix
0017-letter-combinations-of-a-phone-number
0020-valid-parentheses
0022-generate-parentheses
0028-find-the-index-of-the-first-occurrence-in-a-string
0049-group-anagrams
0058-length-of-last-word
0067-add-binary
0072-edit-distance
0076-minimum-window-substring
0079-word-search
0091-decode-ways
0125-valid-palindrome
0131-palindrome-partitioning
0139-word-break
0151-reverse-words-in-a-string
0168-excel-sheet-column-title
0171-excel-sheet-column-number
0187-repeated-dna-sequences
0205-isomorphic-strings
0208-implement-trie-prefix-tree
0211-design-add-and-search-words-data-structure
0212-word-search-ii
0224-basic-calculator
0227-basic-calculator-ii
0241-different-ways-to-add-parentheses
0242-valid-anagram
0249-group-shifted-strings
0257-binary-tree-paths
0269-alien-dictionary
0273-integer-to-english-words
0288-unique-word-abbreviation
0290-word-pattern
0297-serialize-and-deserialize-binary-tree
0301-remove-invalid-parentheses
0344-reverse-string
0383-ransom-note
0387-first-unique-character-in-a-string
0392-is-subsequence
0394-decode-string
0412-fizz-buzz
0424-longest-repeating-character-replacement
0425-word-squares
0434-number-of-segments-in-a-string
0482-license-key-formatting
0567-permutation-in-string
0599-minimum-index-sum-of-two-lists
0642-design-search-autocomplete-system
0648-replace-words
0677-map-sum-pairs
0692-top-k-frequent-words
0696-count-binary-substrings
0720-longest-word-in-dictionary
0749-shortest-completing-word
0753-open-the-lock
0763-partition-labels
0765-serialize-and-deserialize-n-ary-tree
0782-jewels-and-stones
0807-custom-sort-string
0812-rotate-string
0833-find-and-replace-in-string
0874-backspace-string-compare
0953-verifying-an-alien-dictionary
0981-delete-columns-to-make-sorted
1023-time-based-key-value-store
1023-camelcase-matching
1048-longest-string-chain
1055-shortest-way-to-form-string
1119-robot-bounded-in-circle
1123-single-row-keyboard
1272-invalid-transactions
1274-number-of-days-between-two-dates
1302-delete-characters-to-make-fancy-string
1460-number-of-substrings-containing-all-three-characters
1534-minimum-number-of-frogs-croaking
1764-maximum-repeating-substring
1786-count-the-number-of-consistent-strings
1884-minimum-changes-to-make-alternating-binary-string
1987-substrings-of-size-three-with-distinct-characters
2096-step-by-step-directions-from-a-binary-tree-node-to-another
2147-number-of-ways-to-divide-a-long-corridor
2149-remove-colored-pieces-if-both-neighbors-are-the-same-color
2211-count-collisions-on-a-road
2345-minimum-number-of-operations-to-convert-time
2406-decode-the-message
2532-remove-letter-to-equalize-frequency
2547-odd-string-difference
2816-lexicographically-smallest-palindrome
2828-lexicographically-smallest-string-after-substring-operation
2847-find-maximum-number-of-string-pairs
3143-longest-unequal-adjacent-groups-subsequence-i
3309-count-prefix-and-suffix-pairs-i
3312-number-of-changing-keys
3329-find-the-length-of-the-longest-common-prefix
3379-score-of-a-string
3412-permutation-difference-between-two-strings
3484-lexicographically-smallest-string-after-a-swap
3606-coupon-code-validator

Stack

0020-valid-parentheses
0042-trapping-rain-water
0084-largest-rectangle-in-histogram
0085-maximal-rectangle
0094-binary-tree-inorder-traversal
0114-flatten-binary-tree-to-linked-list
0150-evaluate-reverse-polish-notation
0155-min-stack
0173-binary-search-tree-iterator
0224-basic-calculator
0227-basic-calculator-ii
0232-implement-queue-using-stacks
0234-palindrome-linked-list
0341-flatten-nested-list-iterator
0394-decode-string
0445-add-two-numbers-ii
0503-next-greater-element-ii
0636-exclusive-time-of-functions
0739-daily-temperatures
0758-convert-binary-search-tree-to-sorted-doubly-linked-list
0874-backspace-string-compare
0883-car-fleet
1214-two-sum-bsts
1305-number-of-visible-people-in-a-queue
1582-design-browser-history
2211-count-collisions-on-a-road

Array

0001-two-sum
0004-median-of-two-sorted-arrays
0011-container-with-most-water
0015-3sum
0018-4sum
0026-remove-duplicates-from-sorted-array
0027-remove-element
0031-next-permutation
0033-search-in-rotated-sorted-array
0034-find-first-and-last-position-of-element-in-sorted-array
0035-search-insert-position
0036-valid-sudoku
0037-sudoku-solver
0039-combination-sum
0040-combination-sum-ii
0041-first-missing-positive
0042-trapping-rain-water
0045-jump-game-ii
0046-permutations
0047-permutations-ii
0048-rotate-image
0049-group-anagrams
0051-n-queens
0053-maximum-subarray
0054-spiral-matrix
0055-jump-game
0056-merge-intervals
0063-unique-paths-ii
0066-plus-one
0073-set-matrix-zeroes
0074-search-a-2d-matrix
0075-sort-colors
0078-subsets
0079-word-search
0081-search-in-rotated-sorted-array-ii
0084-largest-rectangle-in-histogram
0085-maximal-rectangle
0088-merge-sorted-array
0090-subsets-ii
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0106-construct-binary-tree-from-inorder-and-postorder-traversal
0118-pascals-triangle
0119-pascals-triangle-ii
0120-triangle
0121-best-time-to-buy-and-sell-stock
0122-best-time-to-buy-and-sell-stock-ii
0128-longest-consecutive-sequence
0130-surrounded-regions
0136-single-number
0139-word-break
0150-evaluate-reverse-polish-notation
0152-maximum-product-subarray
0153-find-minimum-in-rotated-sorted-array
0154-find-minimum-in-rotated-sorted-array-ii
0162-find-peak-element
0167-two-sum-ii-input-array-is-sorted
0169-majority-element
0170-two-sum-iii-data-structure-design
0189-rotate-array
0198-house-robber
0200-number-of-islands
0209-minimum-size-subarray-sum
0212-word-search-ii
0213-house-robber-ii
0215-kth-largest-element-in-an-array
0217-contains-duplicate
0219-contains-duplicate-ii
0221-maximal-square
0229-majority-element-ii
0238-product-of-array-except-self
0240-search-a-2d-matrix-ii
0249-group-shifted-strings
0253-meeting-rooms-ii
0269-alien-dictionary
0274-h-index
0281-zigzag-iterator
0283-move-zeroes
0284-peeking-iterator
0286-walls-and-gates
0287-find-the-duplicate-number
0288-unique-word-abbreviation
0289-game-of-life
0300-longest-increasing-subsequence
0322-coin-change
0346-moving-average-from-data-stream
0347-top-k-frequent-elements
0349-intersection-of-two-arrays
0350-intersection-of-two-arrays-ii
0353-design-snake-game
0354-russian-doll-envelopes
0373-find-k-pairs-with-smallest-sums
0379-design-phone-directory
0380-insert-delete-getrandom-o1
0410-split-array-largest-sum
0413-arithmetic-slices
0414-third-maximum-number
0417-pacific-atlantic-water-flow
0425-word-squares
0448-find-all-numbers-disappeared-in-an-array
0452-minimum-number-of-arrows-to-burst-balloons
0454-4sum-ii
0485-max-consecutive-ones
0487-max-consecutive-ones-ii
0490-the-maze
0498-diagonal-traverse
0503-next-greater-element-ii
0505-the-maze-ii
0523-continuous-subarray-sum
0529-minesweeper
0532-k-diff-pairs-in-an-array
0540-single-element-in-a-sorted-array
0542-01-matrix
0561-array-partition
0599-minimum-index-sum-of-two-lists
0636-exclusive-time-of-functions
0643-maximum-average-subarray-i
0648-replace-words
0658-find-k-closest-elements
0673-number-of-longest-increasing-subsequence
0674-longest-continuous-increasing-subsequence
0692-top-k-frequent-words
0695-max-area-of-island
0719-find-k-th-smallest-pair-distance
0720-longest-word-in-dictionary
0723-candy-crush
0724-find-pivot-index
0733-flood-fill
0739-daily-temperatures
0745-find-smallest-letter-greater-than-target
0748-largest-number-at-least-twice-of-others
0749-shortest-completing-word
0753-open-the-lock
0786-search-in-a-sorted-array-of-unknown-size
0792-binary-search
0816-design-hashset
0817-design-hashmap
0833-find-and-replace-in-string
0860-design-circular-queue
0883-car-fleet
0907-koko-eating-bananas
0909-snakes-and-ladders
0924-minimize-malware-spread
0941-sort-array-by-parity
0948-sort-an-array
0953-verifying-an-alien-dictionary
0966-binary-subarrays-with-sum
0971-shortest-bridge
0981-delete-columns-to-make-sorted
1007-minimum-domino-rotations-for-equal-row
1014-k-closest-points-to-origin
1019-squares-of-a-sorted-array
1023-camelcase-matching
1025-minimum-cost-for-tickets
1031-add-to-array-form-of-integer
1036-rotting-oranges
1039-find-the-town-judge
1046-max-consecutive-ones-iii
1048-longest-string-chain
1056-capacity-to-ship-packages-within-d-days
1073-number-of-enclaves
1085-the-earliest-moment-when-everyone-become-friends
1121-partition-array-for-maximum-sum
1126-minimum-cost-to-connect-sticks
1127-last-stone-weight
1137-height-checker
1149-intersection-of-three-sorted-arrays
1168-duplicate-zeros
1171-shortest-path-in-binary-matrix
1221-element-appearing-more-than-25-in-sorted-array
1231-replace-elements-with-greatest-element-on-right-side
1272-invalid-transactions
1305-number-of-visible-people-in-a-queue
1370-count-number-of-nice-subarrays
1380-number-of-closed-islands
1382-calculate-amount-paid-in-taxes
1386-shift-2d-grid
1400-find-winner-on-a-tic-tac-toe-game
1408-find-the-smallest-divisor-given-a-threshold
1421-find-numbers-with-even-number-of-digits
1426-find-n-unique-integers-sum-up-to-zero
1428-jump-game-iii
1445-number-of-sub-arrays-of-size-k-and-average-greater-than-or-equal-to-threshold
1455-filter-restaurants-by-vegan-friendly-price-and-distance
1468-check-if-n-and-its-double-exist
1470-shuffle-the-array
1478-maximum-number-of-events-that-can-be-attended
1548-check-if-all-1s-are-at-least-length-k-places-away
1552-magnetic-force-between-two-balls
1556-make-two-arrays-equal-by-reversing-subarrays
1560-number-of-students-doing-homework-at-a-given-time
1582-design-browser-history
1584-average-salary-excluding-the-minimum-and-maximum-salary
1605-minimum-number-of-days-to-make-m-bouquets
1775-design-an-ordered-stream
1786-count-the-number-of-consistent-strings
1866-restore-the-array-from-adjacent-pairs
1929-concatenation-of-array
1983-maximum-population-year
2015-determine-whether-matrix-can-be-obtained-by-rotation
2038-nearest-exit-from-entrance-in-maze
2047-find-a-peak-element-ii
2054-two-best-non-overlapping-events
2075-brightest-position-on-street
2106-find-greatest-common-divisor-of-array
2122-count-special-quadruplets
2132-convert-1d-array-into-2d-array
2138-sum-of-beauty-in-the-array
2181-smallest-index-with-equal-value
2192-minimum-cost-homecoming-of-a-robot-in-a-grid
2215-finding-3-digit-even-numbers
2265-partition-array-according-to-given-pivot
2277-count-equal-and-divisible-pairs-in-an-array
2386-min-max-game
2402-meeting-rooms-iii
2522-median-of-a-row-wise-sorted-matrix
2524-largest-positive-integer-that-exists-with-its-negative
2547-odd-string-difference
2614-maximum-count-of-positive-integer-and-negative-integer
2626-count-the-number-of-good-subarrays
2664-maximize-greatness-of-an-array
2692-take-gifts-from-the-richest-pile
2767-maximum-sum-with-exactly-k-elements
2779-number-of-adjacent-elements-with-the-same-color
2847-find-maximum-number-of-string-pairs
3034-points-that-intersect-with-cars
3075-maximize-happiness-of-selected-children
3143-longest-unequal-adjacent-groups-subsequence-i
3309-count-prefix-and-suffix-pairs-i
3329-find-the-length-of-the-longest-common-prefix
3350-adjacent-increasing-subarrays-detection-ii
3415-check-if-grid-satisfies-conditions
3421-count-pairs-that-form-a-complete-day-i
3432-count-partitions-with-even-sum-difference
3433-count-mentions-per-user
3515-find-if-digit-game-can-be-won
3531-count-covered-buildings
3578-count-partitions-with-max-min-difference-at-most-k
3583-count-special-triplets
3606-coupon-code-validator

Hash Table

0001-two-sum
0003-longest-substring-without-repeating-characters
0012-integer-to-roman
0013-roman-to-integer
0017-letter-combinations-of-a-phone-number
0036-valid-sudoku
0037-sudoku-solver
0041-first-missing-positive
0049-group-anagrams
0073-set-matrix-zeroes
0076-minimum-window-substring
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0106-construct-binary-tree-from-inorder-and-postorder-traversal
0128-longest-consecutive-sequence
0133-clone-graph
0139-word-break
0141-linked-list-cycle
0142-linked-list-cycle-ii
0146-lru-cache
0169-majority-element
0170-two-sum-iii-data-structure-design
0187-repeated-dna-sequences
0202-happy-number
0205-isomorphic-strings
0208-implement-trie-prefix-tree
0217-contains-duplicate
0219-contains-duplicate-ii
0229-majority-element-ii
0242-valid-anagram
0249-group-shifted-strings
0264-ugly-number-ii
0288-unique-word-abbreviation
0290-word-pattern
0314-binary-tree-vertical-order-traversal
0347-top-k-frequent-elements
0349-intersection-of-two-arrays
0350-intersection-of-two-arrays-ii
0353-design-snake-game
0355-design-twitter
0359-logger-rate-limiter
0379-design-phone-directory
0380-insert-delete-getrandom-o1
0383-ransom-note
0387-first-unique-character-in-a-string
0424-longest-repeating-character-replacement
0448-find-all-numbers-disappeared-in-an-array
0454-4sum-ii
0460-lfu-cache
0508-most-frequent-subtree-sum
0523-continuous-subarray-sum
0532-k-diff-pairs-in-an-array
0567-permutation-in-string
0599-minimum-index-sum-of-two-lists
0648-replace-words
0652-find-duplicate-subtrees
0653-two-sum-iv-input-is-a-bst
0677-map-sum-pairs
0692-top-k-frequent-words
0720-longest-word-in-dictionary
0749-shortest-completing-word
0753-open-the-lock
0763-partition-labels
0782-jewels-and-stones
0807-custom-sort-string
0816-design-hashset
0817-design-hashmap
0833-find-and-replace-in-string
0893-all-nodes-distance-k-in-binary-tree
0924-minimize-malware-spread
0953-verifying-an-alien-dictionary
0966-binary-subarrays-with-sum
1023-time-based-key-value-store
1039-find-the-town-judge
1048-longest-string-chain
1123-single-row-keyboard
1149-intersection-of-three-sorted-arrays
1272-invalid-transactions
1370-count-number-of-nice-subarrays
1400-find-winner-on-a-tic-tac-toe-game
1460-number-of-substrings-containing-all-three-characters
1468-check-if-n-and-its-double-exist
1556-make-two-arrays-equal-by-reversing-subarrays
1722-throne-inheritance
1775-design-an-ordered-stream
1786-count-the-number-of-consistent-strings
1866-restore-the-array-from-adjacent-pairs
1987-substrings-of-size-three-with-distinct-characters
2122-count-special-quadruplets
2215-finding-3-digit-even-numbers
2402-meeting-rooms-iii
2406-decode-the-message
2524-largest-positive-integer-that-exists-with-its-negative
2532-remove-letter-to-equalize-frequency
2547-odd-string-difference
2626-count-the-number-of-good-subarrays
2847-find-maximum-number-of-string-pairs
3034-points-that-intersect-with-cars
3329-find-the-length-of-the-longest-common-prefix
3343-count-numbers-with-unique-digits-ii
3412-permutation-difference-between-two-strings
3421-count-pairs-that-form-a-complete-day-i
3531-count-covered-buildings
3583-count-special-triplets
3606-coupon-code-validator

Math

0002-add-two-numbers
0007-reverse-integer
0009-palindrome-number
0012-integer-to-roman
0013-roman-to-integer
0029-divide-two-integers
0048-rotate-image
0050-powx-n
0062-unique-paths
0066-plus-one
0067-add-binary
0069-sqrtx
0070-climbing-stairs
0150-evaluate-reverse-polish-notation
0168-excel-sheet-column-title
0171-excel-sheet-column-number
0189-rotate-array
0202-happy-number
0224-basic-calculator
0227-basic-calculator-ii
0241-different-ways-to-add-parentheses
0258-add-digits
0263-ugly-number
0264-ugly-number-ii
0273-integer-to-english-words
0279-perfect-squares
0367-valid-perfect-square
0380-insert-delete-getrandom-o1
0400-nth-digit
0412-fizz-buzz
0445-add-two-numbers-ii
0523-continuous-subarray-sum
1014-k-closest-points-to-origin
1031-add-to-array-form-of-integer
1119-robot-bounded-in-circle
1236-n-th-tribonacci-number
1274-number-of-days-between-two-dates
1370-count-number-of-nice-subarrays
1411-convert-binary-number-in-a-linked-list-to-integer
1421-find-numbers-with-even-number-of-digits
1426-find-n-unique-integers-sum-up-to-zero
1444-number-of-steps-to-reduce-a-number-to-zero
1523-count-odd-numbers-in-an-interval-range
2106-find-greatest-common-divisor-of-array
2147-number-of-ways-to-divide-a-long-corridor
2149-remove-colored-pieces-if-both-neighbors-are-the-same-color
2383-add-two-integers
2491-smallest-even-multiple
2704-maximum-difference-by-remapping-a-digit
2752-sum-multiples
3343-count-numbers-with-unique-digits-ii
3432-count-partitions-with-even-sum-difference
3433-count-mentions-per-user
3515-find-if-digit-game-can-be-won
3568-find-the-key-of-the-numbers

Two Pointers

0005-longest-palindromic-substring
0011-container-with-most-water
0015-3sum
0018-4sum
0019-remove-nth-node-from-end-of-list
0026-remove-duplicates-from-sorted-array
0027-remove-element
0028-find-the-index-of-the-first-occurrence-in-a-string
0031-next-permutation
0042-trapping-rain-water
0061-rotate-list
0075-sort-colors
0088-merge-sorted-array
0125-valid-palindrome
0141-linked-list-cycle
0142-linked-list-cycle-ii
0148-sort-list
0151-reverse-words-in-a-string
0167-two-sum-ii-input-array-is-sorted
0170-two-sum-iii-data-structure-design
0189-rotate-array
0202-happy-number
0234-palindrome-linked-list
0253-meeting-rooms-ii
0283-move-zeroes
0287-find-the-duplicate-number
0344-reverse-string
0349-intersection-of-two-arrays
0350-intersection-of-two-arrays-ii
0392-is-subsequence
0532-k-diff-pairs-in-an-array
0567-permutation-in-string
0653-two-sum-iv-input-is-a-bst
0658-find-k-closest-elements
0696-count-binary-substrings
0719-find-k-th-smallest-pair-distance
0723-candy-crush
0763-partition-labels
0874-backspace-string-compare
0908-middle-of-the-linked-list
0941-sort-array-by-parity
1019-squares-of-a-sorted-array
1023-camelcase-matching
1048-longest-string-chain
1055-shortest-way-to-form-string
1168-duplicate-zeros
1214-two-sum-bsts
1468-check-if-n-and-its-double-exist
2265-partition-array-according-to-given-pivot
2524-largest-positive-integer-that-exists-with-its-negative
2664-maximize-greatness-of-an-array
2816-lexicographically-smallest-palindrome

String Matching

0028-find-the-index-of-the-first-occurrence-in-a-string
0572-subtree-of-another-tree
0812-rotate-string
1023-camelcase-matching
1764-maximum-repeating-substring
3309-count-prefix-and-suffix-pairs-i

Binary Search

0004-median-of-two-sorted-arrays
0033-search-in-rotated-sorted-array
0034-find-first-and-last-position-of-element-in-sorted-array
0035-search-insert-position
0069-sqrtx
0074-search-a-2d-matrix
0081-search-in-rotated-sorted-array-ii
0153-find-minimum-in-rotated-sorted-array
0154-find-minimum-in-rotated-sorted-array-ii
0162-find-peak-element
0167-two-sum-ii-input-array-is-sorted
0209-minimum-size-subarray-sum
0240-search-a-2d-matrix-ii
0278-first-bad-version
0287-find-the-duplicate-number
0300-longest-increasing-subsequence
0349-intersection-of-two-arrays
0350-intersection-of-two-arrays-ii
0354-russian-doll-envelopes
0367-valid-perfect-square
0374-guess-number-higher-or-lower
0400-nth-digit
0410-split-array-largest-sum
0532-k-diff-pairs-in-an-array
0540-single-element-in-a-sorted-array
0658-find-k-closest-elements
0719-find-k-th-smallest-pair-distance
0745-find-smallest-letter-greater-than-target
0786-search-in-a-sorted-array-of-unknown-size
0792-binary-search
0907-koko-eating-bananas
1023-time-based-key-value-store
1046-max-consecutive-ones-iii
1055-shortest-way-to-form-string
1056-capacity-to-ship-packages-within-d-days
1149-intersection-of-three-sorted-arrays
1214-two-sum-bsts
1408-find-the-smallest-divisor-given-a-threshold
1468-check-if-n-and-its-double-exist
1552-magnetic-force-between-two-balls
1605-minimum-number-of-days-to-make-m-bouquets
2047-find-a-peak-element-ii
2054-two-best-non-overlapping-events
2522-median-of-a-row-wise-sorted-matrix
2614-maximum-count-of-positive-integer-and-negative-integer
3350-adjacent-increasing-subarrays-detection-ii

Dynamic Programming

0005-longest-palindromic-substring
0010-regular-expression-matching
0022-generate-parentheses
0042-trapping-rain-water
0045-jump-game-ii
0053-maximum-subarray
0055-jump-game
0062-unique-paths
0063-unique-paths-ii
0070-climbing-stairs
0072-edit-distance
0085-maximal-rectangle
0091-decode-ways
0095-unique-binary-search-trees-ii
0118-pascals-triangle
0119-pascals-triangle-ii
0120-triangle
0121-best-time-to-buy-and-sell-stock
0122-best-time-to-buy-and-sell-stock-ii
0131-palindrome-partitioning
0139-word-break
0152-maximum-product-subarray
0198-house-robber
0213-house-robber-ii
0221-maximal-square
0241-different-ways-to-add-parentheses
0264-ugly-number-ii
0279-perfect-squares
0300-longest-increasing-subsequence
0322-coin-change
0333-largest-bst-subtree
0338-counting-bits
0354-russian-doll-envelopes
0392-is-subsequence
0410-split-array-largest-sum
0413-arithmetic-slices
0487-max-consecutive-ones-ii
0542-01-matrix
0673-number-of-longest-increasing-subsequence
0803-cheapest-flights-within-k-stops
1025-minimum-cost-for-tickets
1048-longest-string-chain
1121-partition-array-for-maximum-sum
1236-n-th-tribonacci-number
1764-maximum-repeating-substring
2054-two-best-non-overlapping-events
2147-number-of-ways-to-divide-a-long-corridor
2710-minimum-operations-to-reduce-an-integer-to-0
3143-longest-unequal-adjacent-groups-subsequence-i
3343-count-numbers-with-unique-digits-ii
3578-count-partitions-with-max-min-difference-at-most-k

Memoization

0070-climbing-stairs
0139-word-break
0241-different-ways-to-add-parentheses
1236-n-th-tribonacci-number

Sorting

0015-3sum
0018-4sum
0049-group-anagrams
0056-merge-intervals
0075-sort-colors
0088-merge-sorted-array
0148-sort-list
0169-majority-element
0215-kth-largest-element-in-an-array
0217-contains-duplicate
0229-majority-element-ii
0242-valid-anagram
0253-meeting-rooms-ii
0274-h-index
0314-binary-tree-vertical-order-traversal
0347-top-k-frequent-elements
0349-intersection-of-two-arrays
0350-intersection-of-two-arrays-ii
0354-russian-doll-envelopes
0414-third-maximum-number
0452-minimum-number-of-arrows-to-burst-balloons
0532-k-diff-pairs-in-an-array
0561-array-partition
0642-design-search-autocomplete-system
0658-find-k-closest-elements
0692-top-k-frequent-words
0719-find-k-th-smallest-pair-distance
0720-longest-word-in-dictionary
0748-largest-number-at-least-twice-of-others
0807-custom-sort-string
0833-find-and-replace-in-string
0883-car-fleet
0941-sort-array-by-parity
0948-sort-an-array
1014-k-closest-points-to-origin
1019-squares-of-a-sorted-array
1048-longest-string-chain
1085-the-earliest-moment-when-everyone-become-friends
1137-height-checker
1272-invalid-transactions
1455-filter-restaurants-by-vegan-friendly-price-and-distance
1468-check-if-n-and-its-double-exist
1478-maximum-number-of-events-that-can-be-attended
1552-magnetic-force-between-two-balls
1556-make-two-arrays-equal-by-reversing-subarrays
1584-average-salary-excluding-the-minimum-and-maximum-salary
2054-two-best-non-overlapping-events
2075-brightest-position-on-street
2215-finding-3-digit-even-numbers
2402-meeting-rooms-iii
2524-largest-positive-integer-that-exists-with-its-negative
2664-maximize-greatness-of-an-array
3075-maximize-happiness-of-selected-children
3433-count-mentions-per-user
3531-count-covered-buildings
3606-coupon-code-validator

Tree

0094-binary-tree-inorder-traversal
0095-unique-binary-search-trees-ii
0098-validate-binary-search-tree
0099-recover-binary-search-tree
0100-same-tree
0101-symmetric-tree
0102-binary-tree-level-order-traversal
0103-binary-tree-zigzag-level-order-traversal
0104-maximum-depth-of-binary-tree
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0106-construct-binary-tree-from-inorder-and-postorder-traversal
0110-balanced-binary-tree
0111-minimum-depth-of-binary-tree
0112-path-sum
0113-path-sum-ii
0114-flatten-binary-tree-to-linked-list
0116-populating-next-right-pointers-in-each-node
0129-sum-root-to-leaf-numbers
0173-binary-search-tree-iterator
0199-binary-tree-right-side-view
0226-invert-binary-tree
0230-kth-smallest-element-in-a-bst
0236-lowest-common-ancestor-of-a-binary-tree
0257-binary-tree-paths
0285-inorder-successor-in-bst
0297-serialize-and-deserialize-binary-tree
0314-binary-tree-vertical-order-traversal
0333-largest-bst-subtree
0341-flatten-nested-list-iterator
0366-find-leaves-of-binary-tree
0437-path-sum-iii
0450-delete-node-in-a-bst
0508-most-frequent-subtree-sum
0513-find-bottom-left-tree-value
0543-diameter-of-binary-tree
0572-subtree-of-another-tree
0617-merge-two-binary-trees
0652-find-duplicate-subtrees
0653-two-sum-iv-input-is-a-bst
0662-maximum-width-of-binary-tree
0758-convert-binary-search-tree-to-sorted-doubly-linked-list
0765-serialize-and-deserialize-n-ary-tree
0783-search-in-a-binary-search-tree
0784-insert-into-a-binary-search-tree
0789-kth-largest-element-in-a-stream
0893-all-nodes-distance-k-in-binary-tree
0975-range-sum-of-bst
1079-sum-of-root-to-leaf-binary-numbers
1214-two-sum-bsts
1492-time-needed-to-inform-all-employees
1544-count-good-nodes-in-binary-tree
1722-throne-inheritance
2096-step-by-step-directions-from-a-binary-tree-node-to-another

Depth-First Search

0079-word-search
0094-binary-tree-inorder-traversal
0098-validate-binary-search-tree
0099-recover-binary-search-tree
0100-same-tree
0101-symmetric-tree
0104-maximum-depth-of-binary-tree
0110-balanced-binary-tree
0111-minimum-depth-of-binary-tree
0112-path-sum
0113-path-sum-ii
0114-flatten-binary-tree-to-linked-list
0116-populating-next-right-pointers-in-each-node
0129-sum-root-to-leaf-numbers
0130-surrounded-regions
0133-clone-graph
0199-binary-tree-right-side-view
0200-number-of-islands
0207-course-schedule
0210-course-schedule-ii
0211-design-add-and-search-words-data-structure
0226-invert-binary-tree
0230-kth-smallest-element-in-a-bst
0236-lowest-common-ancestor-of-a-binary-tree
0257-binary-tree-paths
0261-graph-valid-tree
0269-alien-dictionary
0285-inorder-successor-in-bst
0297-serialize-and-deserialize-binary-tree
0314-binary-tree-vertical-order-traversal
0333-largest-bst-subtree
0339-nested-list-weight-sum
0341-flatten-nested-list-iterator
0366-find-leaves-of-binary-tree
0417-pacific-atlantic-water-flow
0437-path-sum-iii
0490-the-maze
0505-the-maze-ii
0508-most-frequent-subtree-sum
0513-find-bottom-left-tree-value
0529-minesweeper
0543-diameter-of-binary-tree
0547-number-of-provinces
0572-subtree-of-another-tree
0617-merge-two-binary-trees
0642-design-search-autocomplete-system
0652-find-duplicate-subtrees
0653-two-sum-iv-input-is-a-bst
0662-maximum-width-of-binary-tree
0684-redundant-connection
0695-max-area-of-island
0733-flood-fill
0758-convert-binary-search-tree-to-sorted-doubly-linked-list
0765-serialize-and-deserialize-n-ary-tree
0766-flatten-a-multilevel-doubly-linked-list
0801-is-graph-bipartite
0803-cheapest-flights-within-k-stops
0813-all-paths-from-source-to-target
0893-all-nodes-distance-k-in-binary-tree
0924-minimize-malware-spread
0971-shortest-bridge
0975-range-sum-of-bst
1073-number-of-enclaves
1079-sum-of-root-to-leaf-binary-numbers
1192-critical-connections-in-a-network
1214-two-sum-bsts
1380-number-of-closed-islands
1428-jump-game-iii
1492-time-needed-to-inform-all-employees
1544-count-good-nodes-in-binary-tree
1576-reorder-routes-to-make-all-paths-lead-to-the-city-zero
1722-throne-inheritance
1866-restore-the-array-from-adjacent-pairs
2096-step-by-step-directions-from-a-binary-tree-node-to-another
2121-find-if-path-exists-in-graph

Binary Tree

0094-binary-tree-inorder-traversal
0095-unique-binary-search-trees-ii
0098-validate-binary-search-tree
0099-recover-binary-search-tree
0100-same-tree
0101-symmetric-tree
0102-binary-tree-level-order-traversal
0103-binary-tree-zigzag-level-order-traversal
0104-maximum-depth-of-binary-tree
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0106-construct-binary-tree-from-inorder-and-postorder-traversal
0110-balanced-binary-tree
0111-minimum-depth-of-binary-tree
0112-path-sum
0113-path-sum-ii
0114-flatten-binary-tree-to-linked-list
0116-populating-next-right-pointers-in-each-node
0129-sum-root-to-leaf-numbers
0173-binary-search-tree-iterator
0199-binary-tree-right-side-view
0226-invert-binary-tree
0230-kth-smallest-element-in-a-bst
0236-lowest-common-ancestor-of-a-binary-tree
0257-binary-tree-paths
0285-inorder-successor-in-bst
0297-serialize-and-deserialize-binary-tree
0314-binary-tree-vertical-order-traversal
0333-largest-bst-subtree
0366-find-leaves-of-binary-tree
0437-path-sum-iii
0450-delete-node-in-a-bst
0508-most-frequent-subtree-sum
0513-find-bottom-left-tree-value
0543-diameter-of-binary-tree
0572-subtree-of-another-tree
0617-merge-two-binary-trees
0652-find-duplicate-subtrees
0653-two-sum-iv-input-is-a-bst
0662-maximum-width-of-binary-tree
0758-convert-binary-search-tree-to-sorted-doubly-linked-list
0783-search-in-a-binary-search-tree
0784-insert-into-a-binary-search-tree
0789-kth-largest-element-in-a-stream
0893-all-nodes-distance-k-in-binary-tree
0975-range-sum-of-bst
1079-sum-of-root-to-leaf-binary-numbers
1214-two-sum-bsts
1544-count-good-nodes-in-binary-tree
2096-step-by-step-directions-from-a-binary-tree-node-to-another

Linked List

0002-add-two-numbers
0019-remove-nth-node-from-end-of-list
0021-merge-two-sorted-lists
0023-merge-k-sorted-lists
0061-rotate-list
0114-flatten-binary-tree-to-linked-list
0116-populating-next-right-pointers-in-each-node
0141-linked-list-cycle
0142-linked-list-cycle-ii
0146-lru-cache
0148-sort-list
0206-reverse-linked-list
0234-palindrome-linked-list
0237-delete-node-in-a-linked-list
0355-design-twitter
0379-design-phone-directory
0445-add-two-numbers-ii
0460-lfu-cache
0758-convert-binary-search-tree-to-sorted-doubly-linked-list
0766-flatten-a-multilevel-doubly-linked-list
0816-design-hashset
0817-design-hashmap
0850-insert-into-a-sorted-circular-linked-list
0860-design-circular-queue
0908-middle-of-the-linked-list
1411-convert-binary-number-in-a-linked-list-to-integer
1582-design-browser-history

Recursion

0002-add-two-numbers
0010-regular-expression-matching
0021-merge-two-sorted-lists
0050-powx-n
0206-reverse-linked-list
0224-basic-calculator
0234-palindrome-linked-list
0241-different-ways-to-add-parentheses
0273-integer-to-english-words
0394-decode-string

Trie

0014-longest-common-prefix
0139-word-break
0208-implement-trie-prefix-tree
0211-design-add-and-search-words-data-structure
0212-word-search-ii
0425-word-squares
0642-design-search-autocomplete-system
0648-replace-words
0677-map-sum-pairs
0692-top-k-frequent-words
0720-longest-word-in-dictionary
1023-camelcase-matching
3309-count-prefix-and-suffix-pairs-i
3329-find-the-length-of-the-longest-common-prefix

Breadth-First Search

0100-same-tree
0101-symmetric-tree
0102-binary-tree-level-order-traversal
0103-binary-tree-zigzag-level-order-traversal
0104-maximum-depth-of-binary-tree
0111-minimum-depth-of-binary-tree
0112-path-sum
0116-populating-next-right-pointers-in-each-node
0130-surrounded-regions
0133-clone-graph
0199-binary-tree-right-side-view
0200-number-of-islands
0207-course-schedule
0210-course-schedule-ii
0226-invert-binary-tree
0261-graph-valid-tree
0269-alien-dictionary
0279-perfect-squares
0286-walls-and-gates
0297-serialize-and-deserialize-binary-tree
0301-remove-invalid-parentheses
0314-binary-tree-vertical-order-traversal
0322-coin-change
0339-nested-list-weight-sum
0417-pacific-atlantic-water-flow
0490-the-maze
0505-the-maze-ii
0513-find-bottom-left-tree-value
0529-minesweeper
0542-01-matrix
0547-number-of-provinces
0617-merge-two-binary-trees
0653-two-sum-iv-input-is-a-bst
0662-maximum-width-of-binary-tree
0684-redundant-connection
0695-max-area-of-island
0733-flood-fill
0753-open-the-lock
0765-serialize-and-deserialize-n-ary-tree
0801-is-graph-bipartite
0803-cheapest-flights-within-k-stops
0813-all-paths-from-source-to-target
0893-all-nodes-distance-k-in-binary-tree
0909-snakes-and-ladders
0924-minimize-malware-spread
0971-shortest-bridge
1036-rotting-oranges
1073-number-of-enclaves
1171-shortest-path-in-binary-matrix
1229-shortest-path-with-alternating-colors
1380-number-of-closed-islands
1428-jump-game-iii
1492-time-needed-to-inform-all-employees
1544-count-good-nodes-in-binary-tree
1576-reorder-routes-to-make-all-paths-lead-to-the-city-zero
2038-nearest-exit-from-entrance-in-maze
2121-find-if-path-exists-in-graph

Bit Manipulation

0029-divide-two-integers
0067-add-binary
0078-subsets
0090-subsets-ii
0136-single-number
0187-repeated-dna-sequences
0190-reverse-bits
0287-find-the-duplicate-number
0338-counting-bits
1444-number-of-steps-to-reduce-a-number-to-zero
1786-count-the-number-of-consistent-strings
2710-minimum-operations-to-reduce-an-integer-to-0

Divide and Conquer

0004-median-of-two-sorted-arrays
0023-merge-k-sorted-lists
0053-maximum-subarray
0105-construct-binary-tree-from-preorder-and-inorder-traversal
0106-construct-binary-tree-from-inorder-and-postorder-traversal
0148-sort-list
0169-majority-element
0190-reverse-bits
0215-kth-largest-element-in-an-array
0240-search-a-2d-matrix-ii
0347-top-k-frequent-elements
0948-sort-an-array
1014-k-closest-points-to-origin

Counting

0169-majority-element
0229-majority-element-ii
0347-top-k-frequent-elements
0383-ransom-note
0387-first-unique-character-in-a-string
0692-top-k-frequent-words
1149-intersection-of-three-sorted-arrays
1534-minimum-number-of-frogs-croaking
1786-count-the-number-of-consistent-strings
1983-maximum-population-year
1987-substrings-of-size-three-with-distinct-characters
2532-remove-letter-to-equalize-frequency
2614-maximum-count-of-positive-integer-and-negative-integer
3421-count-pairs-that-form-a-complete-day-i
3583-count-special-triplets

Sliding Window

0003-longest-substring-without-repeating-characters
0076-minimum-window-substring
0187-repeated-dna-sequences
0209-minimum-size-subarray-sum
0219-contains-duplicate-ii
0413-arithmetic-slices
0424-longest-repeating-character-replacement
0487-max-consecutive-ones-ii
0567-permutation-in-string
0643-maximum-average-subarray-i
0658-find-k-closest-elements
0966-binary-subarrays-with-sum
1046-max-consecutive-ones-iii
1370-count-number-of-nice-subarrays
1445-number-of-sub-arrays-of-size-k-and-average-greater-than-or-equal-to-threshold
1460-number-of-substrings-containing-all-three-characters
1987-substrings-of-size-three-with-distinct-characters
2626-count-the-number-of-good-subarrays
3578-count-partitions-with-max-min-difference-at-most-k

Greedy

0011-container-with-most-water
0045-jump-game-ii
0055-jump-game
0122-best-time-to-buy-and-sell-stock-ii
0253-meeting-rooms-ii
0410-split-array-largest-sum
0452-minimum-number-of-arrows-to-burst-balloons
0561-array-partition
0763-partition-labels
1007-minimum-domino-rotations-for-equal-row
1055-shortest-way-to-form-string
1126-minimum-cost-to-connect-sticks
1478-maximum-number-of-events-that-can-be-attended
2149-remove-colored-pieces-if-both-neighbors-are-the-same-color
2192-minimum-cost-homecoming-of-a-robot-in-a-grid
2345-minimum-number-of-operations-to-convert-time
2664-maximize-greatness-of-an-array
2704-maximum-difference-by-remapping-a-digit
2710-minimum-operations-to-reduce-an-integer-to-0
2767-maximum-sum-with-exactly-k-elements
2816-lexicographically-smallest-palindrome
2828-lexicographically-smallest-string-after-substring-operation
3075-maximize-happiness-of-selected-children
3143-longest-unequal-adjacent-groups-subsequence-i
3484-lexicographically-smallest-string-after-a-swap

Backtracking

0017-letter-combinations-of-a-phone-number
0022-generate-parentheses
0037-sudoku-solver
0039-combination-sum
0040-combination-sum-ii
0046-permutations
0047-permutations-ii
0051-n-queens
0077-combinations
0078-subsets
0079-word-search
0090-subsets-ii
0095-unique-binary-search-trees-ii
0113-path-sum-ii
0131-palindrome-partitioning
0212-word-search-ii
0257-binary-tree-paths
0301-remove-invalid-parentheses
0425-word-squares
0813-all-paths-from-source-to-target

Hash Function

0187-repeated-dna-sequences
0572-subtree-of-another-tree
0816-design-hashset
0817-design-hashmap
3309-count-prefix-and-suffix-pairs-i

Simulation

0054-spiral-matrix
0067-add-binary
0258-add-digits
0289-game-of-life
0353-design-snake-game
0412-fizz-buzz
0498-diagonal-traverse
0723-candy-crush
0874-backspace-string-compare
1119-robot-bounded-in-circle
1382-calculate-amount-paid-in-taxes
1386-shift-2d-grid
1400-find-winner-on-a-tic-tac-toe-game
1929-concatenation-of-array
2132-convert-1d-array-into-2d-array
2211-count-collisions-on-a-road
2265-partition-array-according-to-given-pivot
2386-min-max-game
2402-meeting-rooms-iii
2692-take-gifts-from-the-richest-pile
2847-find-maximum-number-of-string-pairs
3433-count-mentions-per-user

Prefix Sum

0209-minimum-size-subarray-sum
0238-product-of-array-except-self
0253-meeting-rooms-ii
0410-split-array-largest-sum
0523-continuous-subarray-sum
0724-find-pivot-index
0966-binary-subarrays-with-sum
1046-max-consecutive-ones-iii
1370-count-number-of-nice-subarrays
1983-maximum-population-year
2075-brightest-position-on-street
3034-points-that-intersect-with-cars
3432-count-partitions-with-even-sum-difference
3578-count-partitions-with-max-min-difference-at-most-k

Matrix

0036-valid-sudoku
0037-sudoku-solver
0048-rotate-image
0054-spiral-matrix
0063-unique-paths-ii
0073-set-matrix-zeroes
0074-search-a-2d-matrix
0079-word-search
0085-maximal-rectangle
0130-surrounded-regions
0200-number-of-islands
0212-word-search-ii
0221-maximal-square
0240-search-a-2d-matrix-ii
0286-walls-and-gates
0289-game-of-life
0417-pacific-atlantic-water-flow
0490-the-maze
0498-diagonal-traverse
0505-the-maze-ii
0529-minesweeper
0542-01-matrix
0695-max-area-of-island
0723-candy-crush
0733-flood-fill
0909-snakes-and-ladders
0971-shortest-bridge
1036-rotting-oranges
1073-number-of-enclaves
1171-shortest-path-in-binary-matrix
1380-number-of-closed-islands
1386-shift-2d-grid
1400-find-winner-on-a-tic-tac-toe-game
2015-determine-whether-matrix-can-be-obtained-by-rotation
2038-nearest-exit-from-entrance-in-maze
2047-find-a-peak-element-ii
2132-convert-1d-array-into-2d-array
2522-median-of-a-row-wise-sorted-matrix
3415-check-if-grid-satisfies-conditions

Binary Indexed Tree

0673-number-of-longest-increasing-subsequence

Segment Tree

0673-number-of-longest-increasing-subsequence

Merge Sort

0023-merge-k-sorted-lists
0148-sort-list
0948-sort-an-array

Graph

0133-clone-graph
0207-course-schedule
0210-course-schedule-ii
0261-graph-valid-tree
0269-alien-dictionary
0505-the-maze-ii
0547-number-of-provinces
0684-redundant-connection
0801-is-graph-bipartite
0803-cheapest-flights-within-k-stops
0813-all-paths-from-source-to-target
0924-minimize-malware-spread
1039-find-the-town-judge
1192-critical-connections-in-a-network
1229-shortest-path-with-alternating-colors
1576-reorder-routes-to-make-all-paths-lead-to-the-city-zero
1661-minimum-number-of-vertices-to-reach-all-nodes
1738-maximal-network-rank
2121-find-if-path-exists-in-graph

Topological Sort

0207-course-schedule
0210-course-schedule-ii
0269-alien-dictionary

Union Find

0128-longest-consecutive-sequence
0130-surrounded-regions
0200-number-of-islands
0261-graph-valid-tree
0547-number-of-provinces
0684-redundant-connection
0695-max-area-of-island
0801-is-graph-bipartite
0924-minimize-malware-spread
1073-number-of-enclaves
1085-the-earliest-moment-when-everyone-become-friends
1380-number-of-closed-islands
2121-find-if-path-exists-in-graph

Heap (Priority Queue)

0023-merge-k-sorted-lists
0215-kth-largest-element-in-an-array
0253-meeting-rooms-ii
0264-ugly-number-ii
0347-top-k-frequent-elements
0355-design-twitter
0373-find-k-pairs-with-smallest-sums
0505-the-maze-ii
0642-design-search-autocomplete-system
0658-find-k-closest-elements
0692-top-k-frequent-words
0789-kth-largest-element-in-a-stream
0803-cheapest-flights-within-k-stops
0948-sort-an-array
1014-k-closest-points-to-origin
1126-minimum-cost-to-connect-sticks
1127-last-stone-weight
1478-maximum-number-of-events-that-can-be-attended
2054-two-best-non-overlapping-events
2402-meeting-rooms-iii
2692-take-gifts-from-the-richest-pile

Number Theory

0258-add-digits
2106-find-greatest-common-divisor-of-array
2491-smallest-even-multiple

Rolling Hash

0187-repeated-dna-sequences
3309-count-prefix-and-suffix-pairs-i

Enumeration

2122-count-special-quadruplets
2215-finding-3-digit-even-numbers

Design

0146-lru-cache
0155-min-stack
0170-two-sum-iii-data-structure-design
0173-binary-search-tree-iterator
0208-implement-trie-prefix-tree
0211-design-add-and-search-words-data-structure
0232-implement-queue-using-stacks
0281-zigzag-iterator
0284-peeking-iterator
0288-unique-word-abbreviation
0297-serialize-and-deserialize-binary-tree
0341-flatten-nested-list-iterator
0346-moving-average-from-data-stream
0353-design-snake-game
0355-design-twitter
0359-logger-rate-limiter
0379-design-phone-directory
0380-insert-delete-getrandom-o1
0460-lfu-cache
0642-design-search-autocomplete-system
0677-map-sum-pairs
0789-kth-largest-element-in-a-stream
0816-design-hashset
0817-design-hashmap
0860-design-circular-queue
1023-time-based-key-value-store
1582-design-browser-history
1722-throne-inheritance
1775-design-an-ordered-stream

Data Stream

0170-two-sum-iii-data-structure-design
0346-moving-average-from-data-stream
0359-logger-rate-limiter
0642-design-search-autocomplete-system
0789-kth-largest-element-in-a-stream
1582-design-browser-history
1775-design-an-ordered-stream

Counting Sort

0274-h-index
0561-array-partition
0948-sort-an-array
1137-height-checker

Interactive

0278-first-bad-version
0374-guess-number-higher-or-lower
0786-search-in-a-sorted-array-of-unknown-size

Queue

0232-implement-queue-using-stacks
0281-zigzag-iterator
0341-flatten-nested-list-iterator
0346-moving-average-from-data-stream
0353-design-snake-game
0379-design-phone-directory
0387-first-unique-character-in-a-string
0860-design-circular-queue
3578-count-partitions-with-max-min-difference-at-most-k

Bucket Sort

0347-top-k-frequent-elements
0692-top-k-frequent-words
0948-sort-an-array

Quickselect

0215-kth-largest-element-in-an-array
0347-top-k-frequent-elements
1014-k-closest-points-to-origin

Randomized

0380-insert-delete-getrandom-o1

Monotonic Stack

0042-trapping-rain-water
0084-largest-rectangle-in-histogram
0085-maximal-rectangle
0503-next-greater-element-ii
0739-daily-temperatures
0883-car-fleet
1305-number-of-visible-people-in-a-queue

Binary Search Tree

0095-unique-binary-search-trees-ii
0098-validate-binary-search-tree
0099-recover-binary-search-tree
0173-binary-search-tree-iterator
0230-kth-smallest-element-in-a-bst
0285-inorder-successor-in-bst
0333-largest-bst-subtree
0450-delete-node-in-a-bst
0653-two-sum-iv-input-is-a-bst
0758-convert-binary-search-tree-to-sorted-doubly-linked-list
0783-search-in-a-binary-search-tree
0784-insert-into-a-binary-search-tree
0789-kth-largest-element-in-a-stream
0975-range-sum-of-bst
1214-two-sum-bsts

Geometry

1014-k-closest-points-to-origin

Database

0197-rising-temperature
0626-exchange-seats
1292-immediate-food-delivery-ii
1317-monthly-transactions-i
1338-queries-quality-and-percentage
2057-count-salary-categories
2087-confirmation-rate
2127-employees-whose-manager-left-the-company

Doubly-Linked List

0146-lru-cache
0460-lfu-cache
0758-convert-binary-search-tree-to-sorted-doubly-linked-list
0766-flatten-a-multilevel-doubly-linked-list
1582-design-browser-history

Iterator

0173-binary-search-tree-iterator
0281-zigzag-iterator
0284-peeking-iterator
0341-flatten-nested-list-iterator

Radix Sort

0948-sort-an-array

Combinatorics

0062-unique-paths

Game Theory

2149-remove-colored-pieces-if-both-neighbors-are-the-same-color

Ordered Set

2075-brightest-position-on-street

Shortest Path

0505-the-maze-ii
0803-cheapest-flights-within-k-stops

Biconnected Component

1192-critical-connections-in-a-network

Monotonic Queue

3578-count-partitions-with-max-min-difference-at-most-k