Merge pull request #736 from AlgorithmWithGod/JHLEE325

[20250825] BOJ / G4 / 불 / 이준희

Author: ShinHeeEul

JHLEE325/202508/25 BOJ G4 불.md

@@ -0,0 +1,112 @@
+```java
+import java.io.*;
+import java.util.*;
+
+public class Main {
+
+    static int[][] map;
+    static int w, h;
+    static Queue<int[]> fireQ;
+    static Queue<int[]> humanQ;
+    static StringBuilder sb = new StringBuilder();
+    static int[] dr = {-1, 1, 0, 0};
+    static int[] dc = {0, 0, -1, 1};
+    static boolean[][] fireVisited;
+    static boolean[][] humanVisited;
+
+    public static void main(String[] args) throws Exception {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st;
+
+        int T = Integer.parseInt(br.readLine());
+
+        for (int t = 0; t < T; t++) {
+            st = new StringTokenizer(br.readLine());
+            w = Integer.parseInt(st.nextToken());
+            h = Integer.parseInt(st.nextToken());
+
+            map = new int[h][w];
+            fireVisited = new boolean[h][w];
+            humanVisited = new boolean[h][w];
+
+            fireQ = new ArrayDeque<>();
+            humanQ = new ArrayDeque<>();
+
+            int sr = -1, sc = -1;
+
+            for (int i = 0; i < h; i++) {
+                String str = br.readLine();
+                for (int j = 0; j < w; j++) {
+                    char ch = str.charAt(j);
+                    if (ch == '#') {
+                        map[i][j] = 1;
+                    } else {
+                        map[i][j] = 0;
+                        if (ch == '@') {
+                            humanQ.add(new int[]{i, j});
+                            humanVisited[i][j] = true;
+                            sr = i; sc = j;
+                        } else if (ch == '*') {
+                            fireQ.add(new int[]{i, j});
+                            fireVisited[i][j] = true;
+                        }
+                    }
+                }
+            }
+
+            if (sr == 0 || sr == h - 1 || sc == 0 || sc == w - 1) {
+                sb.append("1\n");
+            } else {
+                bfs();
+            }
+        }
+        System.out.print(sb.toString());
+    }
+
+    public static void bfs() {
+        int time = 1;
+
+        while (!humanQ.isEmpty()) {
+            int fs = fireQ.size();
+            for (int i = 0; i < fs; i++) {
+                int[] cur = fireQ.poll();
+                for (int d = 0; d < 4; d++) {
+                    int nr = cur[0] + dr[d];
+                    int nc = cur[1] + dc[d];
+                    if (nr < 0 || nr >= h || nc < 0 || nc >= w) continue;
+                    if (map[nr][nc] == 1 || fireVisited[nr][nc]) continue;
+                    fireVisited[nr][nc] = true;
+                    fireQ.add(new int[]{nr, nc});
+                }
+            }
+
+            int hs = humanQ.size();
+            for (int i = 0; i < hs; i++) {
+                int[] cur = humanQ.poll();
+
+                if (cur[0] == 0 || cur[0] == h - 1 || cur[1] == 0 || cur[1] == w - 1) {
+                    sb.append(time).append('\n');
+                    humanQ.clear();
+                    fireQ.clear();
+                    return;
+                }
+
+                for (int d = 0; d < 4; d++) {
+                    int nr = cur[0] + dr[d];
+                    int nc = cur[1] + dc[d];
+                    if (nr < 0 || nr >= h || nc < 0 || nc >= w) continue;
+                    if (map[nr][nc] == 1) continue;
+                    if (humanVisited[nr][nc]) continue;
+                    if (fireVisited[nr][nc]) continue;
+                    humanVisited[nr][nc] = true;
+                    humanQ.add(new int[]{nr, nc});
+                }
+            }
+            time++;
+        }
+
+        sb.append("IMPOSSIBLE\n");
+    }
+}
+
+```