110-balanced-binary-tree

DevGod

Vtuber

Caution

DevGod needs to write an editorial for this problem!

js

/**
 * 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) {

    let helper = function(root){
        if(!root){ return 0;}
        let left = helper(root.left);
        let right = helper(root.right);

        if(left == -1 || right == -1){ return -1; }
        if(Math.abs(left - right) > 1){ return -1; }

        return Math.max(left, right) + 1;
    }

    return helper(root) != -1;
};