package com.company;

import org.junit.Test;

import java.util.Stack;

public class IsSymmetrical {

public class TreeNode {

int val = 0;

TreeNode left = null;

TreeNode right = null;

public TreeNode(int val) {

this.val = val;

}

}

//{8,6,6,5,7,7,5}

/*boolean isSymmetrical(TreeNode pRoot) {

if (pRoot == null) return true;

if (pRoot.left == null && pRoot.right == null) return true;

return isSymmetrical(pRoot.left, pRoot.right);

}

boolean isSymmetrical(TreeNode leftNode, TreeNode rightNode) {

if (leftNode == null && rightNode == null) return true;

if ((leftNode == null && rightNode != null) ||

(rightNode == null && leftNode != null)) return false;

return leftNode.val == rightNode.val &&

isSymmetrical(leftNode.left, rightNode.right) &&

isSymmetrical(leftNode.right, rightNode.left);

}*/

boolean isSymmetrical(TreeNode pRoot) {

if (pRoot == null) return true;

Stack<TreeNode> mStack = new Stack<>();

mStack.push(pRoot.left);

mStack.push(pRoot.right);

while (!mStack.isEmpty()) {

TreeNode rightNode = mStack.pop();

TreeNode leftNode = mStack.pop();

if (rightNode == null && leftNode == null) continue;

if ((rightNode == null && leftNode != null) ||

leftNode == null && rightNode != null) return false;

if (leftNode.val != rightNode.val) return false;

mStack.push(leftNode.left);

mStack.push(rightNode.right);

mStack.push(leftNode.right);

mStack.push(rightNode.left);

}

return true;

}

@Test

public void test() {

TreeNode pRoot = new TreeNode(0);

TreeNode node1 = new TreeNode(1);

TreeNode node2 = new TreeNode(1);

pRoot.left = node1;

pRoot.right = node2;

System.out.println(isSymmetrical(pRoot));

}

}