135 Candy 分配糖果

Posted 2020-10-29 lina2014

 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?

详见：https://leetcode.com/problems/candy/description/

Java实现：

首先初始化每个人一个糖果，然后遍历两遍，第一遍从左向右遍历，如果右边小盆友的等级高，右边小盆友加一个糖果，这样保证了一个方向上高等级的糖果多。然后再从右向左遍历一遍，如果相邻两个左边的等级高，而左边的糖果又少的话，则左边糖果数为右边糖果数加一。最后再把所有小盆友的糖果数都加起来返回即可。

class Solution {
    public int candy(int[] ratings) {
        int n=ratings.length;
        if(n==0||ratings==null){
            return 0;
        }
        int[] dp=new int[n];
        Arrays.fill(dp,1);
        int candy=0;
        for(int i=1;i<n;++i){
            if(ratings[i]>ratings[i-1]){
                dp[i]=dp[i-1]+1;
            }
        }
        for(int i=n-2;i>=0;--i){
            if(ratings[i]>ratings[i+1]){
                dp[i]=Math.max(dp[i],dp[i+1]+1);
            }
        }
        for(int val:dp){
            candy+=val;
        }
        return candy;
    }
}

参考：https://www.cnblogs.com/grandyang/p/4575026.html