Description
Given an array of integers nums and an integer k, return the total number of subarrays whose sum equals to k.
A subarray is a contiguous non-empty sequence of elements within an array.
Example 1:
Input: nums = [1,1,1], k = 2 Output: 2
Example 2:
Input: nums = [1,2,3], k = 3 Output: 2
Constraints:
1 <= nums.length <= 2 * 104-1000 <= nums[i] <= 1000-107 <= k <= 107
Solution
Python3
class Solution:
def subarraySum(self, nums: List[int], k: int) -> int:
N = len(nums)
s = res = 0
mp = defaultdict(int)
mp[0] = 1
for j, x in enumerate(nums):
s += x
if s - k in mp:
res += mp[s - k]
mp[s] += 1
return res