Subarray Sum Equals K

Intuition

• Difference between this one and Minimum Size Subarray Sum is this one asks for exactly = k and the other one is $\ge$ k, and also Minimum Size Subarray Sum has only positive numbers which makes all the difference.
• Sliding Window doesn’t work because we have negative numbers, and so that messes up our calculation along with [1] and k = 0, since cur_sum would have reset to 0 by this point.
• Note that it has to be cur_sum - k, NOT k - cur_sum, since you are getting a negative number and you wish to see if

Complexity

Runtime

Space

Code

TLE

class Solution:
    def subarraySum(self, nums: List[int], k: int) -> int:
        res = 0
        n = len(nums)
        for starting_point in range(n):
            cur_sum = 0
            for j in range(starting_point, n):
                cur_sum += nums[j]
                if cur_sum == k:
                    res += 1
 
        return res

Notes

Cards

START Basic Front: Subarray Sum Equals K Back:

END

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References

• Subarray Sum Equals K