leetcode226.翻转二叉树

leetcode226.翻转二叉树

题目

翻转一棵二叉树。

用例

     4
   /   \
  2     7
 / \   / \
1   3 6   9

     4
   /   \
  7     2
 / \   / \
9   6 3   1

求解

/**
 * 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
    }
    let tmp_left=root.left
    root.left=root.right
    root.right=tmp_left

    invertTree(root.left)
    invertTree(root.right)
    return root   
};