心得:
這題也是典型的遞迴,題目要求把二元樹整個翻轉過來。
問題:
Invert a binary tree.
12345 4/ \2 7/ \ / \1 3 6 9to
12345 4/ \7 2/ \ / \9 6 3 1
答案:
- 遞迴
1234567891011121314151617181920212223/*** Definition for a binary tree node.* public class TreeNode {* public int val;* public TreeNode left;* public TreeNode right;* public TreeNode(int x) { val = x; }* }*/public class Solution {public TreeNode InvertTree(TreeNode root) {if(root == null){return null;}var left = root.left;var right = root.right;root.left = InvertTree(right);root.right = InvertTree(left);return root;}}