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LeetCode-226

题目

结果

代码

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

public void mirror(TreeNode root) {
if (root == null) {
return;
}
TreeNode tmp = root.left;
mirror(root.left);
mirror(root.right);
root.left = root.right;
root.right = tmp;
}
}

复杂度

时间复杂度:O(n)

空间复杂度:O(n)