997. Find the Town Judge

https://leetcode.com/problems/find-the-town-judge/

Python

Prefix Sum (Two Arrays)

• Use two arrays to store indegree and outdegree edges

class Solution:
    def findJudge(self, n: int, trust: List[List[int]]) -> int:
        indegree = [0] * (n+1)
        outdegree = [0] * (n+1)

        for person, trusted in trust:
            outdegree[person] += 1
            indegree[trusted] += 1

        for i in range(1, n+1):
            if indegree[i] == n-1 and outdegree[i] == 0:
                return i
        return -1