剑指offer No.19 二叉树的镜像 java实现（递归+非递归）

操作给定的二叉树，将其变换为源二叉树的镜像。

[code]二叉树的镜像定义：源二叉树
8
/  \
6   10
/ \  / \
5  7 9 11
镜像二叉树
8
/  \
10   6
/ \  / \
11 9 7  5

非递归 栈实现

[code]/**
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 temp = node.left;
node.left = node.right;
node.right = temp;
}
if(node.left != null) stack.push(node.left);
if(node.right != null) stack.push(node.right);
}
}
}

递归

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

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

}

}
*/
public class Solution {
public void Mirror(TreeNode root) {
if(root == null||(root.left == null && root.right == null))
return;
TreeNode pTemp = root.left;
root.left = root.right;
root.right = pTemp;

if(root.left != null)
Mirror(root.left);
if(root.right != null)
Mirror(root.right);
}
}