135. Candy

JIAKAOBO

LeetCode

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Problem

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.

Code

class Solution {
    public int candy(int[] ratings) {        
        int[] arr = new int[ratings.length];
        
        for(int i = 0; i < ratings.length; i++){
            arr[i] = 1;
        }
        
        for(int i = 1; i < ratings.length; i++){
            if(ratings[i] > ratings[i - 1]){
                arr[i] = arr[i - 1] + 1;
            }
        }
        
        for(int i = ratings.length - 2; i >= 0; i--){
            if(ratings[i] > ratings[i + 1]){
                arr[i] = Math.max(arr[i], arr[i + 1] + 1);
            }
        }
        
        int res = 0;
        for(int a : arr){
            res += a;
        }
        
        return res;
    }
}