👨‍🏫 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;
	}
}