560. Subarray Sum Equals K

560. Subarray Sum Equals K

class Solution:
    def subarraySum(self, nums: List[int], k: int) -> int:
        result=0
        presum=0
        d=defaultdict(int)
        d[0]=1
        for num in nums:
            presum=presum+num
            if presum-k in d:
                result=result+d[presum-k]
            
            d[presum]+=1
        
        return result

统计不同前缀和的出现次数