135. Candy

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mob604756eedb0b 2017-12-27 16:43:00

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135. Candy

题目

 There are N children standing in a line. Each child is assigned a rating value.

You are giving candies to these children subjected to the following requirements:

    Each child must have at least one candy.
    Children with a higher rating get more candies than their neighbors.

What is the minimum candies you must give?

解析

这样前后两个遍历结果，思路
采用一次遍历实现或者其他动态规划的思路实现

class Solution_135 {

		//题意：N个孩子站成一排，每个孩子分配一个分值。给这些孩子派发糖果，满足如下要求：
		//每个孩子至少一个
		//分值更高的孩子比他的相邻位的孩子获得更多的糖果
		//求至少分发多少糖果？
public:
	int candy(vector<int> &ratings) {

		//采用左右遍历两次方法
		const int len = ratings.size();

		if (len==1)
		{
			return len;
		}
		vector<int> res(len,1);
		for (int i = 1; i < ratings.size();i++)
		{
			if (ratings[i]>ratings[i-1]) //右边大于左边
			{
				res[i] = res[i - 1] + 1; //分配的糖果数
			}
		}

		int ret = 0;
		for (int j = len - 2,ret=res[len-1]; j >= 0;j--) //bug  此处ret当做局部变量，
		{
			if (ratings[j]>ratings[j+1]&& res[j]<=res[j+1]) //左边大于右边且左边的糖果少于右边的糖果数
			{
				res[j] = res[j + 1] + 1;
			}
			ret += res[j];
		}

		return ret;
	}
};