leetcode

Subarray Sum Equals K

Subarray Sum Equals K

dict version - 72ms

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class Solution:
    def subarraySum(self, nums, target):
        """
        :type nums: List[int]
        :type k: int
        :rtype: int
        """
        dic = {0:1}
        res = pre_sum = 0
        for num in nums:
            pre_sum += num
            res += dic.get(pre_sum - target, 0)
            dic[pre_sum] = dic.get(pre_sum, 0) + 1
        return res

test code

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In [112]: s = Solution(); t = s.subarraySum([1,1,1], 2); print(t)
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leet code