相关题目：
325. 和等于 k 的最长子数组长度
525. 连续数组
class Solution:"""325. 和等于 k 的最长子数组长度巧用前缀和数组，并优化浅醉和数组为单变量"""def findMaxLength(self, nums: List[int], k: int) -> int:res = 0preSum = 0val2idx = dict()val2idx[0] = -1# 计算前缀和for idx, num in enumerate(nums):preSum += numneed = preSum - kif need in val2idx:res = max(res, idx - val2idx[need])else:val2idx[need] = idxreturn resclass Solution:"""525. 连续数组这道题把0视作-1，题目就可转变为：寻找和为0的最长连续子数组"""def findMaxLength(self, nums: List[int]) -> int:res = 0preSum = 0val2idx = dict()val2idx[0] = -1# 计算前缀和for idx, num in enumerate(nums):preSum += (-1 if num == 0 else 1)if preSum in val2idx:res = max(res, idx - val2idx[preSum])else:val2idx[preSum] = idxreturn res
)
