Adding solution to challenge '547. Number of Provinces' (medium).

Author: rboyd

medium/number-of-provinces/number-of-provinces.py

@@ -0,0 +1,23 @@
+class Solution:
+    def findCircleNum(self, isConnected: List[List[int]]) -> int:
+        n = len(isConnected)
+        parent = [i for i in range(n)]
+        def find(a):
+            if parent[a] != a:
+                parent[a] = find(parent[a])
+            return parent[a]
+        def union(a, b):
+            pa, pb = find(a), find(b)
+            if pa == pb:
+                return 0
+            if pa < pb:
+                parent[pb] = pa
+            else:
+                parent[pa] = pb
+
+        for i in range(n):
+            for j, edge in enumerate(isConnected[i]):
+                if edge != 1:
+                    continue
+                union(i, j)
+        return len(set([find(i) for i in range(n)]))