/** * 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 {TreeNode} */ var invertTree = function(root) { if (root === null) { return null; } var node = root.left; root.left = root.right; root.right = node; if (root.left) { invertTree(root.left); } if (root.right) { invertTree(root.right); } return root; };