solve 3

Author: lylaminju

number-of-connected-components-in-an-undirected-graph/pmjuu.py

@@ -0,0 +1,50 @@
+'''
+n: 노드 개수 / e: 간선 개수
+시간 복잡도: O(n + e)
+공간 복잡도: O(n + e)
+'''
+from typing import List
+
+class Solution:
+    def count_components(self, n: int, edges: List[List[int]]) -> int:
+        graph = {i: [] for i in range(n)}
+        for u, v in edges:
+            graph[u].append(v)
+            graph[v].append(u)
+
+        visited = set()
+        def dfs(node):         
+            visited.add(node)
+
+            for neighbor in graph[node]:
+                if neighbor not in visited:
+                    dfs(neighbor)
+        
+        count = 0
+        for node in graph:
+            if node not in visited:
+                count += 1
+                dfs(node)
+                
+        return count
+
+# Test function
+def test():
+    solution = Solution()
+    test_cases = [
+        (3, [[0, 1], [0, 2]], 1),
+        (6, [[0, 1], [1, 2], [2, 3], [4, 5]], 2),
+        (4, [[0, 1], [2, 3]], 2),
+        (1, [], 1),
+        (4, [[0, 1], [2, 3], [1, 2]], 1)
+    ]
+    
+    for i, (n, edges, expected) in enumerate(test_cases):
+        result = solution.count_components(n, edges)
+        print(f"Test case {i+1}: Input: n={n}, edges={edges} -> Output: {result}, Expected: {expected}")
+        if result != expected:
+            print(f"# Test case {i+1} failed: expected {expected}, got {result}")
+        print("\n")
+    
+# Run tests
+test()