Candy


Problem Statement :


There are n children standing in a line. Each child is assigned a rating value given in the integer array ratings.

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.
Return the minimum number of candies you need to have to distribute the candies to the children.

 

Example 1:

Input: ratings = [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: ratings = [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.
 

Constraints:

n == ratings.length
1 <= n <= 2 * 104
0 <= ratings[i] <= 2 * 104


Solution :



title-img 


                            Solution in C :

int candy(int* ratings, int ratingsSize){
    int arr[ratingsSize];
    for(int i=0;i<ratingsSize;i++)
    {
        arr[i]=1;
    }
    for(int i=1;i<ratingsSize;i++)
    {
        if(ratings[i]>ratings[i-1])
        {
            arr[i]=arr[i-1]+1;
        }
       
    }
    for(int i=ratingsSize-2;i>=0;i--)
    {
        if(ratings[i] > ratings[i + 1]) {
            if(arr[i] <= arr[i + 1]) {
                arr[i] = arr[i + 1] + 1;
            }
        }
    }
    
    int candy=0;
    for(int i=0;i<ratingsSize;i++){
        candy = candy+arr[i];
        }
    return candy;
}
                        


                        Solution in C++ :

class Solution {
public:
    int candy(std::vector<int>& ratings) {
        int n = ratings.size();
        std::vector<int> candies(n, 1);

        for (int i = 1; i < n; ++i) {
            if (ratings[i] > ratings[i - 1]) {
                candies[i] = candies[i - 1] + 1;
            }
        }

        for (int i = n - 2; i >= 0; --i) {
            if (ratings[i] > ratings[i + 1]) {
                candies[i] = std::max(candies[i], candies[i + 1] + 1);
            }
        }

        int totalCandies = 0;
        for (int candy : candies) {
            totalCandies += candy;
        }

        return totalCandies;
    }
};
                    


                        Solution in Java :

class Solution {
    public int candy(int[] ratings) {
        int n = ratings.length;
        int[] candies = new int[n];
        Arrays.fill(candies, 1);

        for (int i = 1; i < n; i++) {
            if (ratings[i] > ratings[i - 1]) {
                candies[i] = candies[i - 1] + 1;
            }
        }

        for (int i = n - 2; i >= 0; i--) {
            if (ratings[i] > ratings[i + 1]) {
                candies[i] = Math.max(candies[i], candies[i + 1] + 1);
            }
        }

        int totalCandies = 0;
        for (int candy : candies) {
            totalCandies += candy;
        }

        return totalCandies;
    }
}
                    


                        Solution in Python : 
                            
class Solution:
    def candy(self, ratings: List[int]) -> int:
        n = len(ratings)
        candies = [1] * n 

        for i in range(1, n):
            if ratings[i] > ratings[i-1]:
                candies[i] = candies[i-1] + 1

        for i in range(n-2, -1, -1):
            if ratings[i] > ratings[i+1]:
                candies[i] = max(candies[i], candies[i+1] + 1)
        
        return sum(candies)


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