number-of-connected-components-in-an-undirected-graph solution (ts)

Author: hi-rachel

number-of-connected-components-in-an-undirected-graph/hi-rachel.ts

@@ -0,0 +1,70 @@
+/**
+ * TC: O(N + E), N: 노드의 개수, E: 간선의 개수
+ * SC: O(N + E)
+ */
+
+// DFS
+function countComponentsDFS(n: number, edges: number[][]): number {
+  const graph: number[][] = Array.from({ length: n }, () => []);
+
+  // 그래프 초기화
+  for (const [u, v] of edges) {
+    graph[u].push(v);
+    graph[v].push(u);
+  }
+
+  const visited = new Set<number>();
+
+  function dfs(node: number) {
+    visited.add(node);
+    for (const neighbor of graph[node]) {
+      if (!visited.has(neighbor)) {
+        dfs(neighbor);
+      }
+    }
+  }
+
+  let components = 0;
+  for (let i = 0; i < n; i++) {
+    if (!visited.has(i)) {
+      components++;
+      dfs(i);
+    }
+  }
+
+  return components;
+}
+
+// BFS
+function countComponentsBFS(n: number, edges: number[][]): number {
+  const graph: number[][] = Array.from({ length: n }, () => []);
+
+  // 그래프 초기화
+  for (const [u, v] of edges) {
+    graph[u].push(v);
+    graph[v].push(u);
+  }
+
+  const visited = new Set<number>();
+  let components = 0;
+
+  for (let i = 0; i < n; i++) {
+    if (!visited.has(i)) {
+      components++;
+      const queue: number[] = [i];
+
+      while (queue.length > 0) {
+        const node = queue.shift();
+        if (node === undefined) continue;
+        if (visited.has(node)) continue;
+        visited.add(node);
+
+        for (const neighbor of graph[node]) {
+          if (!visited.has(neighbor)) queue.push(neighbor);
+        }
+      }
+    }
+  }
+
+  return components;
+}