二叉树的镜像java实现

/**
public class TreeNode {
int val = 0;
TreeNode left = null;
TreeNode right = null;

public TreeNode(int val) {
this.val = val;

}

}
*/
import java.util.*;
public class Solution {
public void Mirror(TreeNode root) {
if(root == null) return;
Stack<TreeNode> stack = new Stack<TreeNode>();
stack.push(root);
while(!stack.empty()) {
TreeNode node = stack.pop();
if(node.left != null || node.right != null) {
TreeNode nodeLeft = node.left;
TreeNode nodeRight = node.right;
node.left = nodeRight;
node.right = nodeLeft;
}
if(node.left != null) stack.push(node.left);
if(node.right != null) stack.push(node.right);
}
}
}