diff --git a/alexgoni/102_Binary_Tree_Level_Order_Traversal.js b/alexgoni/102_Binary_Tree_Level_Order_Traversal.js
new file mode 100644
index 0000000..893aefd
--- /dev/null
+++ b/alexgoni/102_Binary_Tree_Level_Order_Traversal.js
@@ -0,0 +1,37 @@
+// 😢
+
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val, left, right) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.left = (left===undefined ? null : left)
+ *     this.right = (right===undefined ? null : right)
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @return {number[][]}
+ */
+var levelOrder = function (root) {
+  if (!root) return [];
+
+  const result = [];
+  const q = [root];
+
+  while (q.length > 0) {
+    const level = [];
+    const size = q.length;
+
+    for (let i = 0; i < size; i++) {
+      const node = q.shift();
+      level.push(node.val);
+
+      if (node.left) q.push(node.left);
+      if (node.right) q.push(node.right);
+    }
+
+    result.push(level);
+  }
+
+  return result;
+};
diff --git a/alexgoni/139_Word_Break.js b/alexgoni/139_Word_Break.js
new file mode 100644
index 0000000..601f052
--- /dev/null
+++ b/alexgoni/139_Word_Break.js
@@ -0,0 +1,23 @@
+// 😢
+
+/**
+ * @param {string} s
+ * @param {string[]} wordDict
+ * @return {boolean}
+ */
+var wordBreak = function (s, wordDict) {
+  const wordSet = new Set(wordDict);
+  const dp = Array.from({ length: s.length + 1 }).fill(false);
+  dp[0] = true;
+
+  for (let i = 1; i <= s.length; i++) {
+    for (let j = 0; j < i; j++) {
+      if (dp[j] && wordSet.has(s.slice(j, i))) {
+        dp[i] = true;
+        break;
+      }
+    }
+  }
+
+  return dp[s.length];
+};
diff --git a/alexgoni/150_Evaluate_Reverse_Polish_Notation.js b/alexgoni/150_Evaluate_Reverse_Polish_Notation.js
new file mode 100644
index 0000000..454d27d
--- /dev/null
+++ b/alexgoni/150_Evaluate_Reverse_Polish_Notation.js
@@ -0,0 +1,48 @@
+// /**
+//  * @param {string[]} tokens
+//  * @return {number}
+//  */
+// var evalRPN = function(tokens) {
+//     let i = 0;
+
+//     while(tokens.length > 1) {
+//         if(isNaN(tokens[i])) {
+//             let temp;
+
+//             if(tokens[i] === "+") temp = Number(tokens[i-2]) + Number(tokens[i-1]);
+//             if(tokens[i] === "-") temp = Number(tokens[i-2]) - Number(tokens[i-1]);
+//             if(tokens[i] === "*") temp = Number(tokens[i-2]) * Number(tokens[i-1]);
+//             if(tokens[i] === "/") temp = Math.trunc(Number(tokens[i-2]) / Number(tokens[i-1]));
+
+//             tokens.splice(i-2, 3, temp);
+//             i = 0;
+//         }
+
+//         i++;
+//     }
+
+//     return +tokens[0];
+// };
+
+/**
+ * @param {string[]} tokens
+ * @return {number}
+ */
+var evalRPN = function (tokens) {
+  const stack = [];
+
+  for (let token of tokens) {
+    if (!isNaN(token)) stack.push(Number(token));
+    else {
+      const b = stack.pop();
+      const a = stack.pop();
+
+      if (token === "+") stack.push(a + b);
+      if (token === "-") stack.push(a - b);
+      if (token === "*") stack.push(a * b);
+      if (token === "/") stack.push(Math.trunc(a / b));
+    }
+  }
+
+  return stack.pop();
+};
diff --git a/alexgoni/1584_Min_Cost_to_Connect_All_Points.js b/alexgoni/1584_Min_Cost_to_Connect_All_Points.js
new file mode 100644
index 0000000..9882b6d
--- /dev/null
+++ b/alexgoni/1584_Min_Cost_to_Connect_All_Points.js
@@ -0,0 +1,39 @@
+// 😢
+
+/**
+ * @param {number[][]} points
+ * @return {number}
+ */
+var minCostConnectPoints = function (points) {
+  const n = points.length;
+  const visited = Array(n).fill(false);
+  const minDist = Array(n).fill(Infinity);
+  minDist[0] = 0;
+  let result = 0;
+
+  for (let i = 0; i < n; i++) {
+    let currMin = Infinity;
+    let currNode = -1;
+
+    for (let j = 0; j < n; j++) {
+      if (!visited[j] && minDist[j] < currMin) {
+        currMin = minDist[j];
+        currNode = j;
+      }
+    }
+
+    visited[currNode] = true;
+    result += currMin;
+
+    for (let j = 0; j < n; j++) {
+      if (!visited[j]) {
+        const cost =
+          Math.abs(points[currNode][0] - points[j][0]) +
+          Math.abs(points[currNode][1] - points[j][1]);
+        minDist[j] = Math.min(minDist[j], cost);
+      }
+    }
+  }
+
+  return result;
+};
diff --git a/alexgoni/207_Course_Schedule.js b/alexgoni/207_Course_Schedule.js
new file mode 100644
index 0000000..2423e36
--- /dev/null
+++ b/alexgoni/207_Course_Schedule.js
@@ -0,0 +1,34 @@
+// 😢
+
+/**
+ * @param {number} numCourses
+ * @param {number[][]} prerequisites
+ * @return {boolean}
+ */
+var canFinish = function (numCourses, prerequisites) {
+  const graph = Array.from({ length: numCourses }, () => []);
+  for (const [a, b] of prerequisites) {
+    graph[b].push(a);
+  }
+
+  const visited = Array(numCourses).fill(0);
+
+  const hasCycle = (cource) => {
+    if (visited[cource] === 1) return true;
+    if (visited[cource] === 2) return false;
+
+    visited[cource] = 1;
+    for (const neighbor of graph[cource]) {
+      if (hasCycle(neighbor)) return true;
+    }
+    visited[cource] = 2;
+
+    return false;
+  };
+
+  for (let i = 0; i < numCourses; i++) {
+    if (hasCycle(i)) return false;
+  }
+
+  return true;
+};
diff --git a/alexgoni/213_House_Robber_ll.js b/alexgoni/213_House_Robber_ll.js
new file mode 100644
index 0000000..f348bb7
--- /dev/null
+++ b/alexgoni/213_House_Robber_ll.js
@@ -0,0 +1,30 @@
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var rob = function (nums) {
+  if (nums.length <= 3) return Math.max(...nums);
+
+  const firstNums = nums.slice(0, nums.length - 1);
+  const secondNums = nums.slice(1);
+  const firstDp = [firstNums[0], firstNums[1]];
+  const secondDp = [secondNums[0], secondNums[1]];
+
+  for (let i = 2; i < firstNums.length; i++) {
+    if (i === 2) firstDp[i] = firstDp[0] + firstNums[i];
+    else firstDp[i] = Math.max(firstDp[i - 2], firstDp[i - 3]) + firstNums[i];
+  }
+
+  for (let i = 2; i < secondNums.length; i++) {
+    if (i === 2) secondDp[i] = secondDp[0] + secondNums[i];
+    else
+      secondDp[i] = Math.max(secondDp[i - 2], secondDp[i - 3]) + secondNums[i];
+  }
+
+  return Math.max(
+    firstDp[firstNums.length - 1],
+    firstDp[firstNums.length - 2],
+    secondDp[secondNums.length - 1],
+    secondDp[secondNums.length - 2]
+  );
+};
diff --git a/alexgoni/215_Kth_Largest_Element_in_an_Array.js b/alexgoni/215_Kth_Largest_Element_in_an_Array.js
new file mode 100644
index 0000000..e82715b
--- /dev/null
+++ b/alexgoni/215_Kth_Largest_Element_in_an_Array.js
@@ -0,0 +1,96 @@
+// 😢
+
+/**
+ * @param {number[]} nums
+ * @param {number} k
+ * @return {number}
+ */
+var findKthLargest = function (nums, k) {
+  const heap = new MaxBinaryHeap();
+
+  for (const num of nums) {
+    heap.insert(num);
+  }
+
+  for (let i = 0; i < k; i++) {
+    const extractedValue = heap.extractMax();
+    if (i === k - 1) return extractedValue;
+  }
+};
+
+class MaxBinaryHeap {
+  constructor() {
+    this.values = [];
+  }
+
+  insert(value) {
+    this.values.push(value);
+    this.#bubbleUp();
+
+    return this.values;
+  }
+
+  extractMax() {
+    const extractedValue = this.values[0];
+    const poppedValue = this.values.pop();
+
+    if (this.values.length === 0) return extractedValue;
+
+    this.values[0] = poppedValue;
+    this.#sinkDown();
+
+    return extractedValue;
+  }
+
+  #bubbleUp() {
+    let currentIndex = this.values.length - 1;
+    const currentValue = this.values[currentIndex];
+
+    while (currentIndex > 0) {
+      const parentIndex = Math.floor((currentIndex - 1) / 2);
+      const parentValue = this.values[parentIndex];
+
+      if (parentValue >= currentValue) break;
+
+      this.values[parentIndex] = currentValue;
+      this.values[currentIndex] = parentValue;
+
+      currentIndex = parentIndex;
+    }
+  }
+
+  #sinkDown() {
+    let currentIndex = 0;
+    const currentValue = this.values[currentIndex];
+    const length = this.values.length;
+
+    while (true) {
+      let leftChildIndex = currentIndex * 2 + 1;
+      let rightChildIndex = currentIndex * 2 + 2;
+      let leftChildValue, rightChildValue;
+      let swapWith = null;
+
+      if (leftChildIndex < length) {
+        leftChildValue = this.values[leftChildIndex];
+        if (leftChildValue > currentValue) swapWith = leftChildIndex;
+      }
+
+      if (rightChildIndex < length) {
+        rightChildValue = this.values[rightChildIndex];
+        if (
+          (!swapWith && rightChildValue > currentValue) ||
+          (swapWith && rightChildValue > leftChildValue)
+        ) {
+          swapWith = rightChildIndex;
+        }
+      }
+
+      if (!swapWith) break;
+
+      this.values[currentIndex] = this.values[swapWith];
+      this.values[swapWith] = currentValue;
+
+      currentIndex = swapWith;
+    }
+  }
+}
diff --git a/alexgoni/235_Lowest_Common_Ancestor_of_a_Binary_Search_Tree.js b/alexgoni/235_Lowest_Common_Ancestor_of_a_Binary_Search_Tree.js
new file mode 100644
index 0000000..d2c48bc
--- /dev/null
+++ b/alexgoni/235_Lowest_Common_Ancestor_of_a_Binary_Search_Tree.js
@@ -0,0 +1,27 @@
+// 😢
+
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val) {
+ *     this.val = val;
+ *     this.left = this.right = null;
+ * }
+ */
+
+/**
+ * @param {TreeNode} root
+ * @param {TreeNode} p
+ * @param {TreeNode} q
+ * @return {TreeNode}
+ */
+var lowestCommonAncestor = function (root, p, q) {
+  if (p.val < root.val && q.val < root.val) {
+    return lowestCommonAncestor(root.left, p, q);
+  }
+
+  if (p.val > root.val && q.val > root.val) {
+    return lowestCommonAncestor(root.right, p, q);
+  }
+
+  return root;
+};
diff --git a/alexgoni/56_Merge_Intervals.js b/alexgoni/56_Merge_Intervals.js
new file mode 100644
index 0000000..9b74555
--- /dev/null
+++ b/alexgoni/56_Merge_Intervals.js
@@ -0,0 +1,22 @@
+/**
+ * @param {number[][]} intervals
+ * @return {number[][]}
+ */
+var merge = function (intervals) {
+  const result = [];
+  intervals.sort((a, b) => a[0] - b[0]);
+
+  let i = 0;
+  while (i < intervals.length - 1) {
+    if (intervals[i][1] >= intervals[i + 1][0]) {
+      intervals.splice(i, 2, [
+        intervals[i][0],
+        Math.max(intervals[i][1], intervals[i + 1][1]),
+      ]);
+    } else {
+      i++;
+    }
+  }
+
+  return intervals;
+};
diff --git a/alexgoni/572_Subtree_of_Another_Tree.js b/alexgoni/572_Subtree_of_Another_Tree.js
new file mode 100644
index 0000000..893eaf4
--- /dev/null
+++ b/alexgoni/572_Subtree_of_Another_Tree.js
@@ -0,0 +1,30 @@
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val, left, right) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.left = (left===undefined ? null : left)
+ *     this.right = (right===undefined ? null : right)
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @param {TreeNode} subRoot
+ * @return {boolean}
+ */
+var isSubtree = function (root, subRoot) {
+  if (!root) return false;
+
+  if (isSameTree(root, subRoot)) return true;
+
+  return isSubtree(root.left, subRoot) || isSubtree(root.right, subRoot);
+};
+
+function isSameTree(root1, root2) {
+  if (!root1 && !root2) return true;
+  if (!root1 || !root2) return false;
+  if (root1.val !== root2.val) return false;
+
+  return (
+    isSameTree(root1.left, root2.left) && isSameTree(root1.right, root2.right)
+  );
+}