226. Invert Binary Tree

Invert Binary Tree - LeetCodeLeetCode

time: O(n)

space: O(h), worst O(n)

/**
 * 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(node) {
    if (node === null) {
        return null;
    }

    const left = invertTree(node.left);
    const right = invertTree(node.right);

    node.left = right
    node.right = left;

    return node;
};