feat: add ts solution to lc problem: No.323 (doocs#2990)

Author: rain84

solution/0300-0399/0323.Number of Connected Components in an Undirected Graph/README.md

@@ -492,4 +492,47 @@ function countComponents(n: number, edges: number[][]): number {
 
 <!-- solution:end -->
 
+<!-- solution:start -->
+
+### 方法 3: BFS
+
+<!-- tabs:start -->
+
+#### TypeScript
+
+```ts
+function countComponents(n: number, edges: number[][]): number {
+    const g: number[][] = Array.from({ length: n }, () => []);
+    const vis = new Set<number>();
+    let ans = 0;
+
+    for (const [i, j] of edges) {
+        g[i].push(j);
+        g[j].push(i);
+    }
+
+    const dfs = (i: number) => {
+        if (vis.has(i)) return;
+
+        vis.add(i);
+        for (const j of g[i]) {
+            dfs(j);
+        }
+    };
+
+    for (let i = 0; i < n; i++) {
+        if (vis.has(i)) continue;
+
+        dfs(i);
+        ans++;
+    }
+
+    return ans;
+}
+```
+
+<!-- tabs:end -->
+
+<!-- solution:end -->
+
 <!-- problem:end -->

solution/0300-0399/0323.Number of Connected Components in an Undirected Graph/README_EN.md

@@ -487,4 +487,47 @@ function countComponents(n: number, edges: number[][]): number {
 
 <!-- solution:end -->
 
+<!-- solution:start -->
+
+### Solution 3: BFS
+
+<!-- tabs:start -->
+
+#### TypeScript
+
+```ts
+function countComponents(n: number, edges: number[][]): number {
+    const g: number[][] = Array.from({ length: n }, () => []);
+    const vis = new Set<number>();
+    let ans = 0;
+
+    for (const [i, j] of edges) {
+        g[i].push(j);
+        g[j].push(i);
+    }
+
+    const dfs = (i: number) => {
+        if (vis.has(i)) return;
+
+        vis.add(i);
+        for (const j of g[i]) {
+            dfs(j);
+        }
+    };
+
+    for (let i = 0; i < n; i++) {
+        if (vis.has(i)) continue;
+
+        dfs(i);
+        ans++;
+    }
+
+    return ans;
+}
+```
+
+<!-- tabs:end -->
+
+<!-- solution:end -->
+
 <!-- problem:end -->

solution/0300-0399/0323.Number of Connected Components in an Undirected Graph/Solution3.ts

@@ -0,0 +1,28 @@
+function countComponents(n: number, edges: number[][]): number {
+    const g: number[][] = Array.from({ length: n }, () => []);
+    const vis = new Set<number>();
+    let ans = 0;
+
+    for (const [i, j] of edges) {
+        g[i].push(j);
+        g[j].push(i);
+    }
+
+    const dfs = (i: number) => {
+        if (vis.has(i)) return;
+
+        vis.add(i);
+        for (const j of g[i]) {
+            dfs(j);
+        }
+    };
+
+    for (let i = 0; i < n; i++) {
+        if (vis.has(i)) continue;
+
+        dfs(i);
+        ans++;
+    }
+
+    return ans;
+}