package main

import (
	"fmt"
)

// TreeNode ...
type TreeNode struct {
	Val   int
	Left  *TreeNode
	Right *TreeNode
}

func isSymmetricIter(lNode *TreeNode, rNode *TreeNode) bool {
	if lNode == nil || rNode == nil {
		return lNode == rNode
	}
	if lNode.Val != rNode.Val {
		return false
	}
	return isSymmetricIter(lNode.Left, rNode.Right) && isSymmetricIter(lNode.Right, rNode.Left)
}

/**
 * Definition for a binary tree node.
 * type TreeNode struct {
 *     Val int
 *     Left *TreeNode
 *     Right *TreeNode
 * }
 */
func isSymmetric(root *TreeNode) bool {
	if root == nil {
		return true
	}
	return isSymmetricIter(root.Left, root.Right)
}

func main() {
	/**
	 * t1:  5
	 *     / \
	 *    1   4
	 *       / \
	 *      2   3
	 */
	t1l := TreeNode{1, nil, nil}
	t1rl := TreeNode{2, nil, nil}
	t1rr := TreeNode{3, nil, nil}
	t1r := TreeNode{4, &t1rl, &t1rr}
	t1 := &TreeNode{5, &t1l, &t1r}
	/**
	 * t2:   1
	 *     /   \
	 *    2     2
	 *   / \   / \
	 *  4   3 3   4
	 */
	t2ll := TreeNode{4, nil, nil}
	t2lr := TreeNode{3, nil, nil}
	t2l := TreeNode{2, &t2ll, &t2lr}
	t2rl := TreeNode{3, nil, nil}
	t2rr := TreeNode{4, nil, nil}
	t2r := TreeNode{2, &t2rl, &t2rr}
	t2 := &TreeNode{1, &t2l, &t2r}
	fmt.Println(isSymmetric(t1))
	fmt.Println(isSymmetric(t2))
}