Description
https://leetcode.com/problems/subarray-sum-equals-k/
Given an array of integers nums and an integer k, return the total number of continuous subarrays whose sum equals to k.
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
Explanation
We can store the sums in a hashmap and check if sum – k in the hashmap.
Python Solution
class Solution:
def subarraySum(self, nums: List[int], k: int) -> int:
count = 0
sum = 0
map = {}
map[0] = 1
for i in range(0, len(nums)):
sum += nums[i]
if (sum - k) in map:
count += map.get(sum - k)
map[sum] = map.get(sum, 0) + 1
return count- Time complexity: O(N).
- Space complexity: O(N).
test