Subarray Sum Equals K



Given an array of integers and an integer k, you need to find the total number of continuous subarrays whose sum equals tok.

Example 1:

Input:nums = [1,1,1], k = 2Output: 2

Note:

1. The length of the array is in range [1, 20,000].
2. The range of numbers in the array is [-1000, 1000] and the range of the integerk is [-1e7, 1e7].

Solution:

class Solution {
public:
    int subarraySum(vector<int>& nums, int k) {
        int res = 0, n = nums.size();
        for (int i = 0; i < n; ++i) {
            int sum = nums[i];
            if (sum == k) ++res;
            for (int j = i + 1; j < n; ++j) {
                sum += nums[j];
                if (sum == k) ++res;
            }
        }
        return res;
    }
};