剑指offer：平衡二叉树

// 平衡二叉树_判断是否是平衡二叉树.cpp : 定义控制台应用程序的入口点。
//题目描述：判断一棵树是否是平衡二叉树
//    思路：求得每个节点的高度，递归的进行子树判断看是否是平衡二叉树

#include "stdafx.h"
struct TreeNode {
	int val;
	TreeNode *left;
	TreeNode *right;
	TreeNode(int x) : val(x), left(NULL), right(NULL) {}
};
int max(int x, int y) {
	return x > y ? x : y;
}
int abs(int a) {
	return a < 0 ? -a : a;
}
int TreeHeight(TreeNode *current) {
	if (current == NULL)
		return 0;
	int height_left, height_right;
	height_left = TreeHeight(current->left) + 1;
	height_right = TreeHeight(current->right) + 1;
	return max(height_left, height_right);
}
bool IsBalanced_Solution(TreeNode* pRoot) {
	if (pRoot == NULL)
		return true;
	int flag = IsBalanced_Solution(pRoot->left) && IsBalanced_Solution(pRoot->right);
	if (abs(TreeHeight(pRoot->left) - TreeHeight(pRoot->right)) < 2)
		flag = flag && true;
	else
		return false;
	return flag;
}