Java Algorithm

Author: par3k

BOJ_JAVA/out/production/BOJ_JAVA/BOJ/BOJ_16562.class

@@ -0,0 +1,109 @@
+package BOJ;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.*;
+
+public class BOJ_5427 {
+    private static int w, h, step;
+    private static boolean flag;
+    private static char[][] graph;
+    private static int[] dx = {-1, 1, 0, 0};
+    private static int[] dy = {0, 0, -1, 1};
+    private static Queue<Node> queue, fire_queue;
+
+    private static void logic() {
+        while (!fire_queue.isEmpty() || !queue.isEmpty()) {
+            int fqlen = fire_queue.size();
+            for (int s = 0; s < fqlen; s++) {
+                Node f = fire_queue.poll();
+
+                for (int d = 0; d < 4; d++) {
+                    int nx = f.x + dx[d];
+                    int ny = f.y + dy[d];
+
+                    if (0 <= nx && nx < h && 0 <= ny && ny < w) {
+                        if (graph[nx][ny] == '.' || graph[nx][ny] == '@') {
+                            graph[nx][ny] = '*';
+                            fire_queue.add(new Node(nx, ny));
+                        }
+                    }
+                }
+            }
+
+            int qlen = queue.size();
+            if (qlen > 0) {
+                step++;
+
+                for (int s = 0; s < qlen; s++) {
+                    Node n = queue.poll();
+
+                    for (int d = 0; d < 4; d++) {
+                        int nx = n.x + dx[d];
+                        int ny = n.y + dy[d];
+
+                        if (nx < 0 || nx >= h || ny < 0 || ny >= w) {
+                            flag = true;
+                            return;
+                        }
+
+                        if (graph[nx][ny] == '.') {
+                            graph[nx][ny] = '@';
+                            queue.add(new Node(nx, ny));
+                        }
+                    }
+                }
+            } else {
+                return;
+            }
+        }
+    }
+
+
+    public static void main (String[]args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        int T = Integer.parseInt(br.readLine());
+
+        for (int tc = 1; tc <= T; tc++) {
+            StringTokenizer st = new StringTokenizer(br.readLine());
+            w = Integer.parseInt(st.nextToken());
+            h = Integer.parseInt(st.nextToken());
+
+            graph = new char[h][w];
+            flag = false;
+            step = 0;
+
+            for (int i = 0; i < h; i++) {
+                graph[i] = br.readLine().toCharArray();
+            }
+
+            queue = new ArrayDeque<>();
+            fire_queue = new ArrayDeque<>();
+
+
+            for (int i = 0; i < h; i++) {
+                for (int j = 0; j < w; j++) {
+                    if (graph[i][j] == '@') {
+                        queue.add(new Node(i, j));
+                    }
+                    if (graph[i][j] == '*') {
+                        fire_queue.add(new Node(i, j));
+                    }
+                }
+            }
+            logic();
+            System.out.println(flag == true ? step : "IMPOSSIBLE");
+        }
+        br.close();
+    }
+
+    private static class Node {
+        int x, y;
+
+        public Node(int x, int y) {
+            this.x = x;
+            this.y = y;
+        }
+    }
+}