Merge pull request #2021 from AlgorithmWithGod/JHLEE325

[20260314] BOJ / G4 / 연구소 2 / 이준희

Author: ShinHeeEul

JHLEE325/202603/14 BOJ G4 연구소 2.md

@@ -0,0 +1,92 @@
+```java
+import java.io.*;
+import java.util.*;
+
+public class Main {
+
+    static int N, M;
+    static int[][] map;
+    static List<int[]> virus = new ArrayList<>();
+    static int[][] selected;
+    static int empty = 0;
+    static int minTime = Integer.MAX_VALUE;
+    static int[] dx = {-1, 1, 0, 0};
+    static int[] dy = {0, 0, -1, 1};
+
+    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());
+
+        map = new int[N][N];
+        selected = new int[M][2];
+
+        for (int i = 0; i < N; i++) {
+            st = new StringTokenizer(br.readLine());
+            for (int j = 0; j < N; j++) {
+                map[i][j] = Integer.parseInt(st.nextToken());
+                if (map[i][j] == 2) {
+                    virus.add(new int[]{i, j});
+                }
+                if (map[i][j] != 1) {
+                    empty++;
+                }
+            }
+        }
+
+        comb(0, 0);
+
+        System.out.println(minTime == Integer.MAX_VALUE ? -1 : minTime);
+    }
+
+    static void comb(int start, int count) {
+        if (count == M) {
+            bfs();
+            return;
+        }
+
+        for (int i = start; i < virus.size(); i++) {
+            selected[count] = virus.get(i);
+            comb(i + 1, count + 1);
+        }
+    }
+
+    static void bfs() {
+        Queue<int[]> q = new LinkedList<>();
+        int[][] visited = new int[N][N];
+        for (int i = 0; i < N; i++) Arrays.fill(visited[i], -1);
+
+        for (int[] v : selected) {
+            q.add(v);
+            visited[v[0]][v[1]] = 0;
+        }
+
+        int count = 0;
+        int time = 0;
+
+        while (!q.isEmpty()) {
+            int[] cur = q.poll();
+            count++;
+            time = Math.max(time, visited[cur[0]][cur[1]]);
+
+            for (int i = 0; i < 4; i++) {
+                int nx = cur[0] + dx[i];
+                int ny = cur[1] + dy[i];
+
+                if (nx >= 0 && nx < N && ny >= 0 && ny < N) {
+                    if (map[nx][ny] != 1 && visited[nx][ny] == -1) {
+                        visited[nx][ny] = visited[cur[0]][cur[1]] + 1;
+                        q.add(new int[]{nx, ny});
+                    }
+                }
+            }
+        }
+
+        if (count == empty) {
+            minTime = Math.min(minTime, time);
+        }
+    }
+}
+```