leetcode 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?

Example 1:

Input: [1,0,2]
Output: 5
Explanation: You can allocate to the first, second and third child with 2, 1, 2 candies respectively.

Example 2:

Input: [1,2,2]
Output: 4
Explanation: You can allocate to the first, second and third child with 1, 2, 1 candies respectively.
             The third child gets 1 candy because it satisfies the above two conditions.

class Solution {
public:
    int candy(vector<int>& ratings) 
    {
        int n = ratings.size();
        vector<int> candy(n,1);
        int sum=0;
        for(int i=1;i<n;i++)
        {
            if(ratings[i]>ratings[i-1]) candy[i] = candy[i-1]+1;
        }
        for(int i=n-2;i>=0;i--)
        {
            if(ratings[i]>ratings[i+1]) candy[i] = max(candy[i+1]+1,candy[i]);
        }
        sum = accumulate(candy.begin(),candy.end(),0);
        return sum;
    }
};