add Number of Connected Components in an Undirected Graph solution

Author: HoonDongKang

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

@@ -0,0 +1,73 @@
+/**
+ * [Problem]: [3651] Number of Connected Components in an Undirected Graph
+ * (https://www.lintcode.com/problem/3651/)
+ */
+export class Solution {
+    /**
+     * @param n: the number of vertices
+     * @param edges: the edges of undirected graph
+     * @return: the number of connected components
+     */
+    countComponents(n: number, edges: number[][]): number {
+        //시간복잡도 O(n + e)
+        // 공간복잡도 O(n + e)
+        function dfsFunc(n: number, edges: number[][]): number {
+            const visited = new Array(n).fill(false);
+            const graph: number[][] = Array.from({ length: n }, () => []);
+
+            for (const [node, adjacent] of edges) {
+                graph[node].push(adjacent);
+                graph[adjacent].push(node);
+            }
+
+            function dfs(node: number) {
+                visited[node] = true;
+                for (const neighbor of graph[node]) {
+                    if (!visited[neighbor]) {
+                        dfs(neighbor);
+                    }
+                }
+            }
+
+            let count = 0;
+
+            for (let i = 0; i < n; i++) {
+                if (!visited[i]) {
+                    count++;
+                    dfs(i);
+                }
+            }
+
+            return count;
+        }
+        // 시간복잡도 O(n + e)
+        // 공간복잡도 O(n + e)
+        function stackFunc(n: number, edges: number[][]): number {
+            const visited = new Array(n).fill(false);
+            const graph: number[][] = Array.from({ length: n }, () => []);
+            let count = 0;
+
+            for (const [node, adjacent] of edges) {
+                graph[node].push(adjacent);
+                graph[adjacent].push(node);
+            }
+
+            for (let i = 0; i < n; i++) {
+                if (visited[i]) continue;
+                count++;
+                const stack = [i];
+
+                while (stack.length) {
+                    const node = stack.pop()!;
+                    visited[node] = true;
+
+                    for (let adj of graph[node]) {
+                        if (!visited[adj]) stack.push(adj);
+                    }
+                }
+            }
+
+            return count;
+        }
+    }
+}