Merge pull request #1002 from AlgorithmWithGod/lkhyun

[20250929] BOJ / G4 / 여행가자 / 이강현

Author: ShinHeeEul

lkhyun/202509/29 BOJ G4 여행가자.md

@@ -0,0 +1,62 @@
+```java
+import java.util.*;
+import java.io.*;
+
+public class Main{
+    static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+    static BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+    static StringTokenizer st;
+    static StringBuilder sb = new StringBuilder();
+    static int N,M;
+    static int[][] cities;
+    static int[] travel;
+    static Set<Integer> connected = new HashSet<>();
+
+    public static void main(String[] args) throws Exception {
+        N = Integer.parseInt(br.readLine());
+        M = Integer.parseInt(br.readLine());
+        cities = new int[N+1][N+1];
+        travel = new int[M];
+        
+        for (int i = 1; i <= N; i++) {
+            st = new StringTokenizer(br.readLine());
+            for (int j = 1; j <= N; j++) {
+                cities[i][j] = Integer.parseInt(st.nextToken());
+            }
+        }
+
+        st = new StringTokenizer(br.readLine());
+        for (int i = 0; i < M; i++) {
+            travel[i] = Integer.parseInt(st.nextToken());
+        }
+
+        BFS(travel[0]);
+        for (int i = 0; i < M; i++) {
+            if(!connected.contains(travel[i])){
+                bw.write("NO");
+                bw.close();
+                return;
+            }
+        }
+        bw.write("YES");
+        bw.close();
+    }
+    public static void BFS(int start){
+        ArrayDeque<Integer> q = new ArrayDeque<>();
+        boolean[] visited = new boolean[N+1];
+        q.offer(start);
+        visited[start] = true;
+
+        while(!q.isEmpty()){
+            int cur = q.poll();
+            connected.add(cur);
+            
+            for (int i=1;i<=N;i++) {
+                if(cities[cur][i] == 0 || visited[i]) continue;
+                q.offer(i);
+                visited[i] = true;
+            }
+        }
+    }
+}
+```