題目:
請完成一個函數,輸入一個二叉樹,該函數輸出它的鏡像。
例如輸入:
4
/ \
2 7
/ \ / \
1 3 6 9
鏡像輸出:
4
/ \
7 2
/ \ / \
9 6 3 1
示例 1:
輸入:root = [4,2,7,1,3,6,9]
輸出:[4,7,2,9,6,3,1]
限制:
0 <= 節點個數 <= 1000
思路:
遞歸的交換左右子樹
代碼:
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
class Solution {
public TreeNode mirrorTree(TreeNode root) {
if(root == null) {
return null;
}
TreeNode tmp = root.left;
root.left = root.right;
root.right = tmp;
mirrorTree(root.left);
mirrorTree(root.right);
return root;
}
}