[LeetCode] 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?

解题思路：
        1. 对于ratings[i], ratings[i]的数目的大小，取决于ratings[i-1], ratings[i+1]和ratings[i]的大小对比。我们可以简化为，ratings[i-1] vs ratings[i] 或者ratings[i+1] vs ratings[i].
        从左到右扫描数组，candies[i] = candies[i-1] + 1 if ratisngs[i] > ratings[i-1]
          然后第二遍，从右到左，candies[i-1] = candies[i] + 1 if ratings[i-1] > ratisngs[i]
          第二遍，要注意在ratings[i-1] > ratings[i] and candies[i-1] > candies[i], 就不需要更改了candies了。

 
public int candy(int[] ratings) {
        int n = ratings.length;
        if(n == 0) return 0;
        
       int[] candies = new int[n];
       int total = 0;
       candies[0] = 1;
       
       
       for(int i = 1; i < ratings.length; i++){
           if(ratings[i] > ratings[i-1]){
               candies[i] = candies[i-1] + 1;
           }else{
               candies[i] = 1;
           }
       }
       
       total = candies[n - 1];
       
       for(int i = ratings.length - 1; i > 0 ; i--){
           if(ratings[i] < ratings[i-1] && candies[i] >= candies[i-1]){
               candies[i-1] = candies[i] + 1;
           }
               total += candies[i-1];
       }
       
       return total;
           
    }