Candy135.java

package com.freetymekiyan.algorithms.level.hard;

/**
 * There are N children standing in a line. Each child is assigned a rating value.
 * <p>
 * You are giving candies to these children subjected to the following requirements:
 * <p>
 * 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?
 * <p>
 * Analysis:
 * 2 loop
 * time O(n)
 */
class Candy135 {

    public static int candy(int[] ratings) {
        if (ratings == null || ratings.length == 0) {
            return 0;
        }
        int[] nums = new int[ratings.length];
        nums[0] = 1;

        for (int i = 1; i < ratings.length; i++) {
            if (ratings[i] > ratings[i - 1]) {
                nums[i] = nums[i - 1] + 1;
            } else {
                nums[i] = 1;
            }
        }
        int res = nums[ratings.length - 1];

        for (int i = ratings.length - 2; i >= 0; i--) {
            int cur = 1;
            if (ratings[i] > ratings[i + 1]) {
                cur = nums[i + 1] + 1;
            }
            res += Math.max(cur, nums[i]);
            nums[i] = cur;
        }
        return res;
    }

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int[] rateArray = {1, 2, 4, 1, 3};
        int res = candy(rateArray);
        System.out.print(res);
    }

}