[ PS ] : Number of Connected Components in an Undirected Graph

Author: uraflower

number-of-connected-components-in-an-undirected-graph/uraflower.js

@@ -0,0 +1,47 @@
+
+/**
+ * @param n: the number of vertices
+ * @param edges: the edges of undirected graph
+ * @return: the number of connected components
+ */
+const countComponents = function (n, edges) {
+  // graph 만들기
+  const graph = Array.from({ length: n }).map(() => []);
+
+  for (const [u, v] of edges) {
+    graph[u].push(v);
+    graph[v].push(u);
+  }
+
+  // 각 노드 순회하기
+  let count = 0;
+  const visited = new Set();
+
+  for (let i = 0; i < n; i++) {
+    if (visited.has(i)) {
+      continue;
+    }
+
+    count += 1;
+
+    // bfs
+    const queue = [i];
+    visited.add(i);
+
+    while (queue.length) {
+      const u = queue.shift();
+
+      for (const v of graph[u]) {
+        if (!visited.has(v)) {
+          visited.add(v);
+          queue.push(v);
+        }
+      }
+    }
+  }
+
+  return count;
+}
+
+// 시간복잡도: O(E)
+// 공간복잡도: O(V)