[oceanlee-seoul] 24.11.19 (#103)

* 102 / Binary Tree Level Order Traversal / Medium / 60m

* 572 / Subtree of Another Tree / Easy / 30m

Author: oceanlee-seoul

oceanlee-seoul/7week/110_balaced_binary_tree.js

@@ -0,0 +1,32 @@
+/**
+ * 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 {boolean}
+ */
+var isBalanced = function (root) {
+  const checkHeight = (node) => {
+    if (node === null) return 0;
+
+    const leftHeight = checkHeight(node.left);
+    const rightHeight = checkHeight(node.right);
+
+    if (
+      leftHeight === -1 ||
+      rightHeight === -1 ||
+      Math.abs(leftHeight - rightHeight) > 1
+    ) {
+      return -1;
+    }
+
+    return Math.max(leftHeight, rightHeight) + 1;
+  };
+
+  return checkHeight(root) !== -1;
+};

oceanlee-seoul/7week/138_single_number.js

@@ -0,0 +1,17 @@
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var singleNumber = function (nums) {
+  if (nums.length === 1) return nums[0];
+
+  const mapObj = {};
+  for (num of nums) {
+    if (!mapObj[num]) {
+      mapObj[num] = 1;
+    } else {
+      mapObj[num] += 1;
+    }
+  }
+  return +Object.keys(mapObj).find((key) => mapObj[key] === 1);
+};

oceanlee-seoul/9week/102_binary_tree_level_order_traversal.js

@@ -0,0 +1,35 @@
+/**
+ * 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 queue = [root];
+
+  while (queue.length > 0) {
+    const levelSize = queue.length;
+    const levelList = [];
+
+    for (let i = 0; i < levelSize; i++) {
+      const node = queue.shift();
+
+      levelList.push(node.val);
+
+      if (node.left) queue.push(node.left);
+
+      if (node.right) queue.push(node.right);
+    }
+    result.push(levelList);
+  }
+  return result;
+};

oceanlee-seoul/9week/572_subtree_of_another_tree.js

@@ -0,0 +1,28 @@
+/**
+ * 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);
+};
+
+var isSameTree = function (t1, t2) {
+  if (!t1 && !t2) return true;
+  if (!t1 || !t2) return false;
+  if (t1.val !== t2.val) return false;
+
+  return isSameTree(t1.left, t2.left) && isSameTree(t1.right, t2.right);
+};