Method numSubarraysWithSum

Array/BinarySubarraysWithSum.py:31–49

:type A: List[int] :type S: int :rtype: int

(self, A, S)

"""
class Solution(object):
    def numSubarraysWithSum(self, A, S):
        """
        :type A: List[int]
        :type S: int
        :rtype: int
        """
        
        dicts = {0:1}
        
        pre = 0
        result = 0
        
        for i in A:
            pre += i
            
            result += dicts.get(pre-S, 0)
            dicts[pre] = dicts.get(pre, 0) + 1
        
        return result