👨‍🏫 题目地址

🍻 AC code

class Solution {public int subarraySum(int[] nums, int k){int ans = 0;int n = nums.length;int[] s = new int[n + 1];// 前缀和s[0] = 0;s[1] = nums[0];for (int i = 2; i <= n; i++)s[i] = s[i - 1] + nums[i - 1];for (int l = 1; l <= n; l++)// 子数组左边界for (int r = l; r <= n; r++)// 子数组右边界{int x = s[r] - s[l - 1];if (x == k)ans++;}return ans;}
}