135. Candy

难度: Hard

题目描述

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

解题思路

代码实现

解决方案

java

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

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

                target[i] = target[i - 1] + 1;
            } else if (ratings[i] < ratings[i - 1]) {

                for (int j = i; j > 0; j--) {
                    if (ratings[j] < ratings[j - 1]&&target[j]>=target[j - 1]) {
                        target[j - 1]++;
                        continue;
                    }
                    break;
                }
            }

        }
        int sum = 0;
        for (int i = 0; i < n; i++) {
            sum += target[i];
        }
        return sum;

    }
}