Improved task 1353.

Author: javadev

README.md

@@ -2646,7 +2646,7 @@ implementation 'com.github.javadev:leetcode-in-java:1.12'
 | 1357 |[Apply Discount Every n Orders](src.save/main/java/g1301_1400/s1357_apply_discount_every_n_orders/Cashier.java)| Medium | Array, Hash_Table, Design | 174 | 58.82
 | 1356 |[Sort Integers by The Number of 1 Bits](src.save/main/java/g1301_1400/s1356_sort_integers_by_the_number_of_1_bits/Solution.java)| Easy | Array, Sorting, Bit_Manipulation, Counting, Programming_Skills_I_Day_11_Containers_and_Libraries | 10 | 65.50
 | 1354 |[Construct Target Array With Multiple Sums](src.save/main/java/g1301_1400/s1354_construct_target_array_with_multiple_sums/Solution.java)| Hard | Array, Heap_Priority_Queue | 2 | 100.00
-| 1353 |[Maximum Number of Events That Can Be Attended](src.save/main/java/g1301_1400/s1353_maximum_number_of_events_that_can_be_attended/Solution.java)| Medium | Array, Greedy, Heap_Priority_Queue | 70 | 21.66
+| 1353 |[Maximum Number of Events That Can Be Attended](src.save/main/java/g1301_1400/s1353_maximum_number_of_events_that_can_be_attended/Solution.java)| Medium | Array, Greedy, Heap_Priority_Queue | 53 | 99.53
 | 1352 |[Product of the Last K Numbers](src.save/main/java/g1301_1400/s1352_product_of_the_last_k_numbers/ProductOfNumbers.java)| Medium | Array, Math, Design, Queue, Data_Stream | 24 | 60.43
 | 1351 |[Count Negative Numbers in a Sorted Matrix](src.save/main/java/g1301_1400/s1351_count_negative_numbers_in_a_sorted_matrix/Solution.java)| Easy | Array, Binary_Search, Matrix, Binary_Search_I_Day_8 | 1 | 49.66
 | 1349 |[Maximum Students Taking Exam](src.save/main/java/g1301_1400/s1349_maximum_students_taking_exam/Solution.java)| Hard | Array, Dynamic_Programming, Matrix, Bit_Manipulation, Bitmask | 4 | 76.98

src.save/main/java/g1301_1400/s1353_maximum_number_of_events_that_can_be_attended/Solution.java

@@ -1,29 +1,33 @@
 package g1301_1400.s1353_maximum_number_of_events_that_can_be_attended;
 
 // #Medium #Array #Greedy #Heap_Priority_Queue
-// #2022_03_21_Time_70_ms_(21.66%)_Space_99.6_MB_(39.91%)
+// #2022_08_19_Time_53_ms_(99.53%)_Space_99.5_MB_(52.91%)
 
 import java.util.Arrays;
-import java.util.PriorityQueue;
+import java.util.Comparator;
 
 public class Solution {
     public int maxEvents(int[][] events) {
-        Arrays.sort(events, (a, b) -> a[0] != b[0] ? a[0] - b[0] : a[1] - b[1]);
-        PriorityQueue<Integer> heap = new PriorityQueue<>();
-        int maxEvents = 0;
-        int i = 0;
-        for (int day = 1; day <= 100000; day++) {
-            while (i < events.length && events[i][0] == day) {
-                heap.offer(events[i++][1]);
-            }
-            while (!heap.isEmpty() && heap.peek() < day) {
-                heap.poll();
-            }
-            if (!heap.isEmpty()) {
-                heap.poll();
-                maxEvents++;
+        Arrays.sort(events, Comparator.comparingInt(e -> e[1]));
+        int[] root = new int[events[events.length - 1][1] + 2];
+        for (int i = 1; i < root.length; i++) {
+            root[i] = i;
+        }
+        int res = 0;
+        for (int[] e : events) {
+            int nxtAvailable = find(root, e[0]);
+            if (nxtAvailable <= e[1]) {
+                res++;
+                root[nxtAvailable] = find(root, nxtAvailable + 1);
             }
         }
-        return maxEvents;
+        return res;
+    }
+
+    private int find(int[] root, int i) {
+        if (root[i] != i) {
+            return root[i] = find(root, root[i]);
+        }
+        return i;
     }
 }