LeetCode 135 Candy (贪心 构造)

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?

题目链接：https://leetcode.com/problems/candy/

题目分析：先从左到右贪心构造，根据rating的大小尽可能少的发糖，然后从右向左修正一下即可

public class Solution {    public int candy(int[] ratings) {        int len = ratings.length;        if (len < 2) {            return len;        }        int[] candy = new int[len + 1];        candy[0] = 1;        for (int i = 1; i < len; i ++) {            if (ratings[i] > ratings[i - 1]) {                candy[i] = candy[i - 1] + 1;            }            else if (candy[i] == candy[i - 1]){                candy[i] = candy[i - 1];            }            else {                candy[i] = 1;            }        }        int ans = 0;        for (int i = len - 1; i > 0; i --) {            if (candy[i] >= candy[i - 1] && ratings[i] < ratings[i - 1]) {                candy[i - 1] = Math.max(candy[i - 1], candy[i] + 1);            }            ans += candy[i];        }        return ans + candy[0];    }}