The judge is a node in the graph with only indegrees, no outdegrees. We process all edges and count the indegrees vs the outdegrees. The judge will have n - 1 indegrees and 0 outdegrees.
The solution is as follows:
class Solution:
def findJudge(self, n: int, trust: List[List[int]]) -> int:
score = [0] * (n + 1)
for u, v in trust:
score[u] -= 1
score[v] += 1
for node in range(1, n + 1):
if score[node] == n - 1:
return node
return -1_ Time Complexity:
O(e) - Where e is the number of edges.
_ Space Complexity:
O(n) - Where n is the number of nodes.