Subarray Sum Equals K

01 · Question

Given an array of integers nums and an integer k, return the total number of subarrays whose sum equals k.

02 · Solution

Reference solution

1def subarraySum(nums: List[int], k: int) -> int:
2    count = {0: 1}
3    pref = 0
4    res = 0
5    
6    for x in nums:
7        pref += x
8        need = pref - k
9        res += count.get(need, 0)
10        count[pref] = count.get(pref, 0) + 1
11    
12    return res

Range Sum Query - Immutable

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