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997. Find the Town Judge.py

@@ -0,0 +1,20 @@
+class Solution:
+    def findJudge(self, N: int, trust: List[List[int]]) -> int:
+        if N == 1:
+            return 1
+        believe = {}
+        believed = {}
+
+        for a, b in trust:
+            if believe.get(a):
+                believe[a] += 1
+            else:
+                believe[a] = 1
+            if believed.get(b):
+                believed[b] += 1
+            else:
+                believed[b] = 1
+        for k, v in believed.items():
+            if v == N - 1 and believe.get(k, 0) == 0:
+                return k
+        return -1