29-kokeunho

kokeunho/README.md

@@ -29,4 +29,5 @@
 | 25차시 | 2025.05.11 | 그리디 알고리즘 | [팔](https://www.acmicpc.net/problem/1105) | [#100](https://github.com/AlgoLeadMe/AlgoLeadMe-12/pull/100) |
 | 26차시 | 2025.05.19 | 분할 정복 | [별 찍기 - 10](https://www.acmicpc.net/problem/2447) | [#102](https://github.com/AlgoLeadMe/AlgoLeadMe-12/pull/102) |
 | 28차시 | 2025.07.01 | 구현 | [스도쿠](https://www.acmicpc.net/problem/2580) |[#116](https://github.com/AlgoLeadMe/AlgoLeadMe-12/pull/116) |
+| 29차시 | 2025.07.21 | 그래프 탐색 | [불!](https://www.acmicpc.net/problem/4179) |[#118](https://github.com/AlgoLeadMe/AlgoLeadMe-12/pull/118) |
 ---

kokeunho/그래프 탐색/29-kokeunho.java

@@ -0,0 +1,84 @@
+import java.util.*;
+
+public class Main {
+    static int R, C;
+    static int escapeCount = Integer.MAX_VALUE;
+    static char[][] map;
+    static int[][] fireCount;
+    static boolean[][] visited;
+    static int[] dx = {-1, 1, 0, 0};
+    static int[] dy = {0, 0, -1, 1};
+
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+
+        R = sc.nextInt();
+        C = sc.nextInt();
+        map = new char[R][C];
+        List<int[]> firePos = new ArrayList<>();
+        int jx = 0, jy = 0;
+        for (int i = 0; i < R; i++) {
+            String line = sc.next();
+            for (int j = 0; j < C; j++) {
+                map[i][j] = line.charAt(j);
+                if (map[i][j] == 'J') {
+                    jx = i;
+                    jy = j;
+                }
+                if (map[i][j] == 'F') {
+                    firePos.add(new int[]{i, j});
+                }
+            }
+        }
+        fireCount = new int[R][C];
+        for (int i = 0; i < R; i++) {
+            Arrays.fill(fireCount[i], Integer.MAX_VALUE);
+        }
+        for (int[] pos : firePos) {
+            fireBfs(pos[0], pos[1]);
+        }
+        visited = new boolean[R][C];
+        jihoonBfs(jx, jy);
+
+        System.out.println(escapeCount == Integer.MAX_VALUE ? "IMPOSSIBLE" : escapeCount);
+    }
+    static void fireBfs (int x, int y) {
+        Queue<int[]> queue = new LinkedList<>();
+        fireCount[x][y] = 0;
+        queue.add(new int[]{x, y});
+
+        while(!queue.isEmpty()) {
+            int[] current = queue.poll();
+            for (int i = 0; i < 4; i++) {
+                int nx = current[0] + dx[i];
+                int ny = current[1] + dy[i];
+                if (nx >= 0 && nx < R && ny >= 0 && ny < C
+                        && fireCount[nx][ny] > fireCount[current[0]][current[1]]+1 && map[nx][ny] != '#') {
+                    queue.add(new int[]{nx, ny});
+                    fireCount[nx][ny] = fireCount[current[0]][current[1]]+1;
+                }
+            }
+        }
+    }
+    static void jihoonBfs (int x, int y) {
+        Queue<int[]> queue = new LinkedList<>();
+        visited[x][y] = true;
+        queue.add(new int[]{x, y, 0});
+
+        while(!queue.isEmpty()) {
+            int[] current = queue.poll();
+            for (int i = 0; i < 4; i++) {
+                int nx = current[0] + dx[i];
+                int ny = current[1] + dy[i];
+                if (nx < 0 || nx >= R || ny < 0 || ny >= C) {
+                    escapeCount = Math.min(escapeCount, current[2] + 1);
+                    continue;
+                }
+                if (!visited[nx][ny] && map[nx][ny] != '#' && current[2] + 1 < fireCount[nx][ny]) {
+                    queue.add(new int[]{nx, ny, current[2] + 1});
+                    visited[nx][ny] = true;
+                }
+            }
+        }
+    }
+}