package leetcode

import (
	"github.com/halfrost/LeetCode-Go/structures"
)

// TreeNode define
type TreeNode = structures.TreeNode

/**
 * Definition for a binary tree node.
 * type TreeNode struct {
 *     Val int
 *     Left *TreeNode
 *     Right *TreeNode
 * }
 */

func isMirror(left *TreeNode, right *TreeNode) bool {
	if left == nil && right == nil {
		return true
	}

	if left == nil || right == nil {
		return false
	}

	return (left.Val == right.Val) && isMirror(left.Left, right.Right) && isMirror(left.Right, right.Left)
}

func isSymmetric(root *TreeNode) bool {
	if root == nil {
		return true
	}

	return isMirror(root.Left, root.Right)
}