# 997. Find the Town Judge """ in a town, there are 'n' people labeled from 1 to 'n'. there is a rumor that one of these people is secretly the town judge. if the town judge exists, then: the town judge trusts nobody. everybody (except the judge) trusts the judge. given: array 'trust' where 'trust[i]' = [ai, bi] representing the the person labeled ai trusts the person labeled bi. return label of judge, if they exist. """ class Solution(object): def findJudge(self, n, trust): """ :type n: int :type trust: List[List[int]] :rtype: int """ cnt = [0] * (n + 1) for i, j in trust: cnt[i] -= 1 cnt[j] += 1 for i in range(1, n + 1): if cnt[i] == n - 1: return i return -1 if __name__ == "__main__": obj = Solution() print(obj.findJudge(n=2, trust=[[1, 2]])) print(obj.findJudge(n=3, trust=[[1, 3], [2, 3]])) print(obj.findJudge(n=3, trust=[[1, 3], [2, 3], [3, 1]]))