solve : number of conntected components in an undirected graph

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

@@ -0,0 +1,23 @@
+# O(n+e) where n is number of nodes and e is the number of edges.
+# O(n+e) where n is number of nodes and e is the number of edges.
+class Solution:
+    def countComponents(self, numNodes: int, connections: List[List[int]]) -> int:
+        adjacencyList = [[] for _ in range(numNodes)]
+        for src, dst in connections:
+            adjacencyList[src].append(dst)
+            adjacencyList[dst].append(src)
+
+        visitedNodes = set()
+
+        def depthFirstSearch(node):
+            visitedNodes.add(node)
+            for neighbor in adjacencyList[node]:
+                if neighbor not in visitedNodes:
+                    depthFirstSearch(neighbor)
+
+        componentCount = 0
+        for node in range(numNodes):
+            if node not in visitedNodes:
+                componentCount += 1
+                depthFirstSearch(node)
+        return componentCount