LeetCode-in-All
560. Subarray Sum Equals K
Medium
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
Solution
from collections import defaultdict
class Solution:
def subarraySum(self, nums: List[int], k: int) -> int:
sub_num = {0:1}
total, count = 0, 0
for n in nums:
total += n
if total - k in sub_num:
count += sub_num[total-k]
sub_num[total] = 1 + sub_num.get(total, 0)
return count