0965-univalued-binary-tree.js

/**
 * 965. Univalued Binary Tree
 * https://leetcode.com/problems/univalued-binary-tree/
 * Difficulty: Easy
 *
 * A binary tree is uni-valued if every node in the tree has the same value.
 *
 * Given the root of a binary tree, return true if the given tree is uni-valued, or false otherwise.
 */

/**
 * 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 isUnivalTree = function(root) {
  const traverse = n => !n ? true : n.val === root.val && isUnivalTree(n);
  return traverse(root.left) && traverse(root.right);
};