未排序正数数组中累加和为给定值的最长子数组的长度

给定一个数组arr，该数组无序，但每个值均为正数，再给定一个正数k。求arr的所有子数组中所有元素相加和为k的最长子数组的长度

例如，arr = [1, 2, 1, 1, 1], k = 3

累加和为3的最长子数组为[1, 1, 1]，所以结果返回3

import java.util.Scanner;

public class Main {

private static int solve(int[] arr, int aim) {
if (arr == null || arr.length == 0) {
return 0;
        }
int ret = 0;

int sum = arr[0];
int l = 0, r = 0;
while (l <= r) {
if (sum == aim) {
ret = Math.max(ret, r - l + 1);
sum -= arr[l++];
            } else if (sum > aim) {
sum -= arr[l++];
            } else {
r++;
if (r == arr.length) {
break;
                }
sum += arr[r];
            }
        }
return ret;
    }

public static void main(String[] args) {
Scanner in = new Scanner(System.in);
while (in.hasNext()) {
int n = in.nextInt();
int aim = in.nextInt();
int[] arr = new int[n];
for (int i = 0; i < n; ++i) {
arr[i] = in.nextInt();
            }
System.out.println(solve(arr, aim));
        }
    }
}

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