110. Balanced Binary Tree

Author: zj

code/110. Balanced Binary Tree/README.md

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+# 110. Balanced Binary Tree
+Given a binary tree, determine if it is height-balanced.
+
+For this problem, a height-balanced binary tree is defined as a binary tree in which the depth of the two subtrees of every node never differ by more than 1.

code/110. Balanced Binary Tree/index.js

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+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val) {
+ *     this.val = val;
+ *     this.left = this.right = null;
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @return {boolean}
+ */
+var isBalanced = function(root) {
+    if(root === null) return true;
+    function depth(root){
+        if(root === null) return 0;
+        return Math.max(depth(root.left),depth(root.right))+1
+    }
+    var left = depth(root.left);
+    var right = depth(root.right);
+    return Math.abs(left - right) <= 1 && isBalanced(root.left) && isBalanced(root.right);
+};