Minimum candies required to distribute among children with ratings

Problem: 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:

Input: [2, 1, 0, 2, 3, 1, 6]
Output: 14
Explanation: You can allocate 3, 2, 1, 2, 3, 1, 2 candies respectively.

Approach: Looks like Trapping water problem. We can use the same approach here.

        public static int Candy(int[] ratings)

        {

            int[] candies = new int[ratings.Length];

            System.Array.Fill(candies, 1);

            for (int i = 1; i < ratings.Length; ++i)

            {

                if (ratings[i] > ratings[i - 1])

                {

                    candies[i] = candies[i - 1] + 1;

                }

            }

            int totalCandies = candies[candies.Length - 1];

            for (int i = candies.Length - 2; i >= 0; --i)

            {

                if (ratings[i] > ratings[i + 1])

                {

                    candies[i] = Math.Max(candies[i], candies[i + 1] + 1);

                }

                totalCandies += candies[i];

            }

            return totalCandies;

        }