Merge pull request #2724 from cyxiwai/kama105

更新补充了kama0105.有向图的完全可达性的Java版本

Author: youngyangyang04

problems/kamacoder/0105.有向图的完全可达性.md

@@ -294,37 +294,52 @@ int main() {
 import java.util.*;
 
 public class Main {
+    public static List<List<Integer>> adjList = new ArrayList<>();
 
-    public static void dfs(List<List<Integer>> graph, int key, boolean[] visited) {
-        for (int neighbor : graph.get(key)) {
-            if (!visited[neighbor]) {  // Check if the next node is not visited
-                visited[neighbor] = true;
-                dfs(graph, neighbor, visited);
-            }
+    public static void dfs(boolean[] visited, int key) {
+        if (visited[key]) {
+            return;
         }
-    }
-
-    public static void main(String[] args) {
-        Scanner scanner = new Scanner(System.in);
-        int n = scanner.nextInt();
-        int m = scanner.nextInt();
-
-        List<List<Integer>> graph = new ArrayList<>();
-        for (int i = 0; i <= n; i++) {
-            graph.add(new ArrayList<>());
+        visited[key] = true;
+        List<Integer> nextKeys = adjList.get(key);
+        for (int nextKey : nextKeys) {
+            dfs(visited, nextKey);
         }
+    }
 
-        for (int i = 0; i < m; i++) {
-            int s = scanner.nextInt();
-            int t = scanner.nextInt();
-            graph.get(s).add(t);
+    public static void bfs(boolean[] visited, int key) {
+        Queue<Integer> queue = new LinkedList<Integer>();
+        queue.add(key);
+        visited[key] = true;
+        while (!queue.isEmpty()) {
+            int curKey = queue.poll();
+            List<Integer> list = adjList.get(curKey);
+            for (int nextKey : list) {
+                if (!visited[nextKey]) {
+                    queue.add(nextKey);
+                    visited[nextKey] = true;
+                }
+            }
         }
+    }
 
-        boolean[] visited = new boolean[n + 1];
-        visited[1] = true;  // Process node 1 beforehand
-        dfs(graph, 1, visited);
-
-        for (int i = 1; i <= n; i++) {
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        int vertices_num = sc.nextInt();
+        int line_num = sc.nextInt();
+        for (int i = 0; i < vertices_num; i++) {
+            adjList.add(new LinkedList<>());
+        }//Initialization
+        for (int i = 0; i < line_num; i++) {
+            int s = sc.nextInt();
+            int t = sc.nextInt();
+            adjList.get(s - 1).add(t - 1);
+        }//构造邻接表
+        boolean[] visited = new boolean[vertices_num];
+        dfs(visited, 0);
+//        bfs(visited, 0);
+
+        for (int i = 0; i < vertices_num; i++) {
             if (!visited[i]) {
                 System.out.println(-1);
                 return;
@@ -334,7 +349,6 @@ public class Main {
     }
 }
 
-
 ```