题解 | #牛牛的果实收集#

import java.util.*;


public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param trees int整型一维数组
     * @param M int整型
     * @return int整型
     */
    public int maxFruits (int[] trees, int M) {
        //前缀和数组
        int n = trees.length;
        int[] sum = new int[n + 1];
        for (int i = 0; i < trees.length ; i++) {
            sum[i + 1] = sum[i] + trees[i];
        }

        int pre = -1;
        for (int i = 0; i <= n; i++) {
            for (int j = 0; j < i ; j++) {
                int sumdiff = sum[i] - sum[j];
                if (sumdiff <= M) {
                    if (pre == -1) pre = sumdiff;
                    else {
                        pre = Math.max(pre, sumdiff);
                    }
                }
            }
        }

        return pre;

    }
}