[20250822] BOJ / G1 / 열쇠 / 이준희

Author: JHLEE325

JHLEE325/202508/22 BOJ G1 열쇠.md

@@ -0,0 +1,114 @@
+```java
+import java.io.*;
+import java.util.*;
+
+public class Main {
+
+    static int h, w;
+    static char[][] map;
+    static boolean[][] visited;
+    static boolean[] key;
+    static List<int[]>[] door;
+    static final int[] dr = {-1, 1, 0, 0};
+    static final int[] dc = {0, 0, -1, 1};
+
+    public static void main(String[] args) throws Exception {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringBuilder out = new StringBuilder();
+
+        int T = Integer.parseInt(br.readLine().trim());
+        for(int t=0;t<T;t++){
+            StringTokenizer st = new StringTokenizer(br.readLine());
+            h = Integer.parseInt(st.nextToken());
+            w = Integer.parseInt(st.nextToken());
+
+            map = new char[h + 2][w + 2];
+            for (int i = 0; i < h + 2; i++) Arrays.fill(map[i], '.');
+
+            for (int r = 1; r <= h; r++) {
+                String line = br.readLine();
+                for (int c = 1; c <= w; c++) {
+                    map[r][c] = line.charAt(c - 1);
+                }
+            }
+
+            key = new boolean[26];
+            door = new ArrayList[26];
+            for (int i = 0; i < 26; i++) door[i] = new ArrayList<>();
+
+            String keys = br.readLine().trim();
+            if (!keys.equals("0")) {
+                for (int i = 0; i < keys.length(); i++) {
+                    char ch = keys.charAt(i);
+                    if ('a' <= ch && ch <= 'z') key[ch - 'a'] = true;
+                }
+            }
+
+            out.append(bfs()).append('\n');
+        }
+
+        System.out.print(out.toString());
+    }
+
+    static int bfs() {
+        visited = new boolean[h + 2][w + 2];
+        Deque<int[]> q = new ArrayDeque<>();
+        q.offer(new int[]{0, 0});
+        visited[0][0] = true;
+
+        int docs = 0;
+
+        while (!q.isEmpty()) {
+            int[] cur = q.poll();
+            int r = cur[0], c = cur[1];
+
+            for (int d = 0; d < 4; d++) {
+                int nr = r + dr[d];
+                int nc = c + dc[d];
+
+                if (nr < 0 || nr >= h + 2 || nc < 0 || nc >= w + 2) continue;
+                if (visited[nr][nc]) continue;
+
+                char ch = map[nr][nc];
+
+                if (ch == '*') continue;
+
+                if ('A' <= ch && ch <= 'Z') {
+                    int idx = ch - 'A';
+                    if (!key[idx]) {
+                        door[idx].add(new int[]{nr, nc});
+                        continue;
+                    }
+                }
+
+                if ('a' <= ch && ch <= 'z') {
+                    int idx = ch - 'a';
+                    if (!key[idx]) {
+                        key[idx] = true;
+                        for (int[] pos : door[idx]) {
+                            int rr = pos[0], cc = pos[1];
+                            if (!visited[rr][cc]) {
+                                visited[rr][cc] = true;
+                                q.offer(new int[]{rr, cc});
+                            }
+                        }
+                        door[idx].clear();
+                    }
+                    map[nr][nc] = '.';
+                }
+
+                if (ch == '$') {
+                    docs++;
+                    map[nr][nc] = '.';
+                }
+
+                visited[nr][nc] = true;
+                q.offer(new int[]{nr, nc});
+            }
+        }
+
+        return docs;
+    }
+}
+
+```