LeetCode 135. Candy--贪心算法

题目链接

135. Candy

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：

这个题难度是hard，其实比较简单，开一个candy[]，从左到右，从右到左遍历一次就搞定了，第一次遍历时，如果后一个的权值大于前一个，则candy数也要大一个，反之，candy数等于1。

第一次遍历后，candy[]中还存在一种违反规则的情况：ratings[i] < ratings[i-1] && candy[i-1] <= candy[i]，反向遍历时依次修改。

代码：

class Solution {public:    int candy(vector<int>& ratings) {        int size = ratings.size();        int *candy = new int[size];        candy[0] = 1;        for (int i = 1; i < size; i++) {            if (ratings[i] > ratings[i-1]) candy[i] = candy[i-1] + 1;            else candy[i] = 1;        }        for (int i = size-1; i > 0; i--) {            if (ratings[i] < ratings[i-1] && candy[i-1] <= candy[i])                candy[i-1] = candy[i] + 1;        }        int count = 0;        for (int i = 0; i < size; i++) count += candy[i];        return count;    }};