这题算一个简单题了。
思路很简单，递归求解的过程:
- 先把当前根节点的左右子树换掉；
- 然后递归换自己的左右子树即可；
例子:
递归代码:
public class Solution {
public void Mirror(TreeNode root) {
if (root == null)
return;
TreeNode t = root.left;
root.left = root.right;
root.right = t;
Mirror(root.left);
Mirror(root.right);
}
}非递归也可以，意思一样:
import java.util.Stack;
public class Solution {
public void Mirror(TreeNode root) {
if (root == null)
return;
Stack<TreeNode>stack = new Stack<>();
stack.push(root);
while (!stack.isEmpty()) {
TreeNode cur = stack.pop();
if (cur.left != null || cur.right != null) {
TreeNode t = cur.left;
cur.left = cur.right;
cur.right = t;
}
if (cur.left != null)
stack.push(cur.left);
if (cur.right != null)
stack.push(cur.right);
}
}
}