Problem Statement
Invert a binary tree.
4 / \ 2 7 / \ / \ 1 3 6 9
to
4 / \ 7 2 / \ / \ 9 6 3 1
Thinking
交换二叉树左右子树,主要还是注意递归结束条件。
Solution
/**
* 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) {
TreeNode tmp;
if(root != null){
tmp = root.left;
root.left = root.right;
root.right = tmp;
}
else
return null;
invertTree(root.left);
invertTree(root.right);
return root;
}
}