[LeetCode]--226. Invert Binary Tree

Invert a binary tree.

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

to

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

Trivia: This problem was inspired by this original tweet by Max Howell: Google: 90% of our engineers use the software you wrote (Homebrew), but you can’t invert a binary tree on a whiteboard so fuck off.

这个题很容易想到递归求解左右子树，不多说，上代码：

/** * Definition for a binary tree node. * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode(int x) { val = x; } * } */ public class Solution { public TreeNode invertTree(TreeNode root) { if (root == null) return null; TreeNode temp = root.left; root.left = root.right; root.right = temp; invertTree(root.left); invertTree(root.right); return root; } }

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