135_candy.md

135 - Candy

leetcode

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.

Solution

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