3197

이준휘/n3197.java

@@ -0,0 +1,123 @@
+package baekjoon2024September;
+
+import java.util.*;
+import java.io.*;
+
+public class n3197 {
+
+    static class Node {
+        int x, y;
+        Node(int x, int y) {
+            this.x = x;
+            this.y = y;
+        }
+    }
+
+    static int r, c;
+    static int[][] dirs = { {1, 0}, {-1, 0}, {0, 1}, {0, -1} };
+
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st = new StringTokenizer(br.readLine());
+
+        r = Integer.parseInt(st.nextToken());
+        c = Integer.parseInt(st.nextToken());
+
+        char[][] map = new char[r][c];
+        boolean[][] visited = new boolean[r][c];
+
+        Queue<Node> swanQueue = new LinkedList<>();
+        Queue<Node> nextSwanQueue = new LinkedList<>();
+        Queue<Node> iceQueue = new LinkedList<>();
+        int[] swans = new int[4];
+        int swanCount = 0;
+
+        for (int i = 0; i < r; i++) {
+            String line = br.readLine();
+            for (int j = 0; j < c; j++) {
+                map[i][j] = line.charAt(j);
+                if (map[i][j] == 'L') {
+                    if (swanCount == 0) {
+                        swans[0] = i;
+                        swans[1] = j;
+                        swanQueue.offer(new Node(i, j));
+                        visited[i][j] = true;
+                    } else {
+                        swans[2] = i;
+                        swans[3] = j;
+                    }
+                    map[i][j] = '.';
+                    swanCount++;
+                }
+
+                if (map[i][j] == '.') {
+                    iceQueue.offer(new Node(i, j));
+                }
+            }
+        }
+
+        int days = 0;
+
+        while (true) {
+            if (swanBFS(map, swans[2], swans[3], swanQueue, nextSwanQueue, visited)) {
+                System.out.println(days);
+                break;
+            }
+
+            iceQueue = meltIce(map, iceQueue);
+
+            swanQueue = nextSwanQueue;
+            nextSwanQueue = new LinkedList<>();
+            days++;
+        }
+    }
+
+    static boolean swanBFS(char[][] map, int L2x, int L2y, Queue<Node> swanQueue, Queue<Node> nextSwanQueue, boolean[][] visited) {
+        while (!swanQueue.isEmpty()) {
+            Node n = swanQueue.poll();
+            int x = n.x;
+            int y = n.y;
+
+            for (int[] dir : dirs) {
+                int nx = x + dir[0];
+                int ny = y + dir[1];
+
+                if (nx >= 0 && ny >= 0 && nx < r && ny < c && !visited[nx][ny]) {
+                    visited[nx][ny] = true;
+
+                    if (nx == L2x && ny == L2y) {
+                        return true;
+                    }
+
+                    if (map[nx][ny] == '.') {
+                        swanQueue.offer(new Node(nx, ny));
+                    } else if (map[nx][ny] == 'X') {
+                        nextSwanQueue.offer(new Node(nx, ny));
+                    }
+                }
+            }
+        }
+        return false;
+    }
+
+    static Queue<Node> meltIce(char[][] map, Queue<Node> iceQueue) {
+        Queue<Node> newIceQueue = new LinkedList<>();
+
+        while (!iceQueue.isEmpty()) {
+            Node n = iceQueue.poll();
+            int x = n.x;
+            int y = n.y;
+
+            for (int[] dir : dirs) {
+                int nx = x + dir[0];
+                int ny = y + dir[1];
+
+                if (nx >= 0 && ny >= 0 && nx < r && ny < c && map[nx][ny] == 'X') {
+                    map[nx][ny] = '.';
+                    newIceQueue.offer(new Node(nx, ny));
+                }
+            }
+        }
+        return newIceQueue;
+    }
+}