997_Find_the_Town_Judge

Author: Partho Biswas

README.md

@@ -541,6 +541,7 @@ BFS, DFS, Dijkstra, Floyd–Warshall, Bellman-Ford, Kruskal, Prim's, Minimum Spa
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+|35| **[997. Find the Town Judge](https://tinyurl.com/y7875kls)** | [Python](https://tinyurl.com/wu6rdaw/997_Find_the_Town_Judge.py), [Swift](https://tinyurl.com/wuja3c4/997_Find_the_Town_Judge.swift) | --- | Easy |📌  |
 
 
 </p>

leetcode.com/python/997_Find_the_Town_Judge.py

@@ -0,0 +1,42 @@
+from collections import defaultdict
+
+class Solution(object):
+    def findJudge(self, N, trust):
+        """
+        :type N: int
+        :type trust: List[List[int]]
+        :rtype: int
+        """
+
+        graph = defaultdict(list)
+
+        for i in range(1, N + 1):
+            graph[i] = []
+
+        for trustPair in trust:
+            parent, child = trustPair
+            graph[parent].append(child)
+
+        judges = []
+        # Checks for first condition. If someone doesn't trust anyone then he/she is a probable candidate for town judge
+        for i in range(1, N + 1):
+            if not graph[i] or len(graph[i]) == 0:
+                judges.append(i)
+
+        # Violets second conditions. Because there is someone else or noone that doesn't truse the town judge
+        if len(judges) != 1:
+            return - 1
+
+        # Checking for third condition
+        for i in range(1, N + 1):
+            childSet = set(graph[i])
+            if judges[-1] != i and judges[-1] not in childSet:
+                return -1
+
+        return judges[-1]
+
+
+"""
+outDegree/edgeList is 0
+
+"""