LeetCode560 和为 K 的子数组

LeetCode560 和为 K 的子数组

前缀和 + 哈希

class Solution:
    def subarraySum(self, nums: List[int], k: int) -> int:

        pre_count, pre, ans = {}, 0, 0
        pre_count[0] = 1

        for c in nums:
            pre += c
            if (pre - k) in pre_count: ans += pre_count[pre - k]
            if pre in pre_count: pre_count[pre] += 1
            else: pre_count[pre] = 1

        return ans