Leetcode - Candy

Candy

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?

public class Solution {
    public int candy(int[] ratings) {
        int len = ratings.length;
        if(len == 0 || len == 1)    return len;
        
        // start with every child already has one candy
        int min = len;
        int[] candies = new int[len];
        
        // scan from head + 1 to tail, compare each child with their next neighbos's rating
        int cur = 0;
        for(int i = 1; i < len; i++) {
            if(ratings[i - 1] < ratings[i])
                cur++;
            else
                cur = 0;
            candies[i] = cur;
        }
        
        // scan from tail - 1 to head, do the same process as above loop
        cur = 0;
        for(int i = len - 2; i >= 0; i--) {
            if(ratings[i] > ratings[i + 1])
                cur++;
            else
                cur = 0;
            // no need to store another candies array again, just compare each node and store the max 
            // (why max: candy num of this position should match with both left and right neighbors)
            min += Math.max(candies[i], cur);
        }
        
        // add the candy num of the tail position, since the loop for add a sum didn't cover that position
        min += candies[len - 1];
        
        return min;
    }
}

Many thanks to : http://blog.csdn.net/violet_program/article/details/12233949