LeetCode Algorithm 997. Find the town judge

Topic link ：997. Find the judge in town

Ideas

Algorithm ： Count
data structure ： chart
Ideas ： Count the in and out degrees of each node , The degree of n-1, The degree of 0 The node of is the town judge .

Code

Python

from collections import Counter
from typing import List


class Solution:
	def findJudge(self, n: int, trust: List[List[int]]) -> int:
		ans, in_degree, out_degree = -1, Counter(), Counter()
		for (start, end) in trust:
			in_degree[end] += 1
			out_degree[start] += 1
		for i in range(1, n + 1):
			if in_degree[i] == n - 1 and out_degree[i] == 0:
				ans = i
		return ans