[220323] BOJ_DFS_BFS_효율적인 해킹

GnuPark/PS/BOJ/DFS_BFS/효율적인_해킹_1325.java

@@ -0,0 +1,67 @@
+package BOJ.DFS_BFS;
+
+import java.io.*;
+import java.util.*;
+
+public class 효율적인_해킹_1325 {
+    static int n, m;
+    static int ans;
+    static boolean visit[];
+    static int arr[];
+    static ArrayList<Integer>[] graph;
+
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st = new StringTokenizer(br.readLine());
+        n = Integer.parseInt(st.nextToken());
+        m = Integer.parseInt(st.nextToken());
+        graph = new ArrayList[n+1];
+        arr = new int[n+1];
+        for (int i = 1; i <= n; i++) {
+            graph[i] = new ArrayList<>();
+        }
+
+        for (int i = 0; i < m; i++) {
+            st = new StringTokenizer(br.readLine());
+            int s = Integer.parseInt(st.nextToken());
+            int e = Integer.parseInt(st.nextToken());
+
+            graph[e].add(s);
+        }
+
+        for (int i = 1; i <= n; i++) {
+            visit = new boolean[n + 1];
+            bfs(i);
+        }
+        StringBuffer sb = new StringBuffer();
+        for (int i = 1; i < arr.length; i++) {
+            if (arr[i] == ans){
+                sb.append(i + " ");
+            }
+        }
+        System.out.println(sb.toString());
+
+    }
+
+    public static void bfs(int index){
+        Queue<Integer> q = new LinkedList<Integer>();
+        q.offer(index);
+        visit[index] = true;
+
+        while (!q.isEmpty()) {
+            int now = q.poll();
+
+            for (int v : graph[now]){
+                if(!visit[v]) {
+                    visit[v] = true;
+                    arr[index] ++;
+                    q.offer(v);
+                }
+            }
+        }
+        if (ans < arr[index]){
+            ans = arr[index];
+        }
+
+    }
+}