1601. Maximum Number of Achievable Transfer Requests

https://leetcode.com/problems/maximum-number-of-achievable-transfer-requests/

Python

from itertools import combinations


class Solution:
    def maximumRequests(self, n: int, requests: List[List[int]]) -> int:
        unchanged = sum([1 for req in requests if req[0] == req[1]])
        reqs = [req for req in requests if req[0] != req[1]]

        ans = 0
        for i in range(len(reqs)+1):
            for combs in list(combinations(reqs, i)):
                if not combs:
                    continue

                movement = [0] * n
                for egress, ingress in combs:
                    movement[egress] += 1
                    movement[ingress] -= 1

                if set(movement) == {0}:
                    ans = max(ans, len(combs))

        return ans + unchanged