[LeetCode OJ] 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?

class Solution {
public:
    int candy(vector<int> &ratings) {
        vector<int> candy_number(ratings.size(), 1);
        //不用迭代器，改用下标索引实现，这样代码看起来更加简洁
        for(int i=1; i<ratings.size(); ++i)
        {
           //保障当右边的rating比左边的高时，则右边分得的糖果比左边多
            if( ratings[i] > ratings[i-1])      //eg：输入[4 2 3 4 1],最少的分法是[2 1 2 3 1],分发9个糖果
                candy_number[i] = (candy_number[i] > candy_number[i-1]+1) ? candy_number[i] : candy_number[i-1]+1;
        }
        

        for(int i=ratings.size()-2; i>=0; --i)   
        {
            //保障当左边的rating比右边的高时，则左边分得的糖果比右边多
            if( ratings[i] > ratings[i+1])
                candy_number[i] = (candy_number[i] > candy_number[i+1]+1) ? candy_number[i] : candy_number[i+1]+1;
        }

        int total=0;
        for(int i=0; i!=ratings.size(); ++i)
            total = total + candy_number[i];

        return total;
    }
};