27、二叉树的镜像

操作给定的二叉树，将其变换为源二叉树的镜像。

题目链接：https://www.nowcoder.com/practice/564f4c26aa584921bc75623e48ca3011

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

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

    }

}
*/


public class Solution {
    
    // 递归方式
    public void Mirror(TreeNode root) {
        if(root!=null){
            if(root.left!=null || root.right!=null){
                TreeNode tmp = root.left;
                root.left = root.right;
                root.right = tmp;
            }
            Mirror(root.left);
            Mirror(root.right);
        }
    }
}


    // 循环方式
    public void Mirror(TreeNode root) {
        if(root!=null){
            java.util.Queue<TreeNode> queue = new java.util.LinkedList<TreeNode>();
            queue.add(root);
            while(!queue.isEmpty()){
                TreeNode tmp = queue.poll();
                TreeNode left = tmp.left;
                tmp.left = tmp.right;
                tmp.right = left;
                if(tmp.left!=null) queue.add(tmp.left);
                if(tmp.right!=null) queue.add(tmp.right);
            }
        }
    }