[C#][LeetCode][Easy] 226. Invert Binary Tree

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.

1
2


1
2
3
4
5
6

4
>
> / \
>
> 2 7
1
2
3
4
5


> / \ / \
>
> 1 3 6 9

to

1
2

4

/ \

7 2

/ \ / \

9 6 3 1

1
2
3
4
5
6



答案:

1. 遞迴

/**

* 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;
}

}

`