candy.java

/**
  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:
    1. Each child must have at least one candy.
    2. Children with a higher rating get more candies than their neighbors.
  What is the minimum candies you must give?
*/
import java.util.*;

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] = candies[i+1] + 1;
        }
    }
    return Arrays.stream(candies).sum();
}