[BOJ] 아기상어2 / 실버2 / 50분

11월/2주차/BOJ_17086_아기상어2/sonda2356.java

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+package Silver;
+
+import java.io.BufferedReader;
+import java.io.InputStreamReader;
+import java.util.ArrayDeque;
+import java.util.StringTokenizer;
+
+public class S17086 {
+    public static int N, M;
+    public static int[][] map;
+    public static int[][] dist;
+
+    public static int[] dx = {-1,-1,-1, 0, 1, 1, 1, 0};
+    public static int[] dy = {-1, 0, 1, 1, 1, 0, -1, -1};
+
+    public static void main(String[] args) throws Exception {
+        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st = new StringTokenizer(in.readLine());
+        N = Integer.parseInt(st.nextToken());
+        M = Integer.parseInt(st.nextToken());
+        map = new int[N][M];
+        dist = new int[N][M];
+        ArrayDeque<int[]> q = new ArrayDeque<>();
+        for (int r = 0; r < N; r++) {
+            st = new StringTokenizer(in.readLine());
+            for (int c = 0; c < M; c++) {
+                map[r][c] = Integer.parseInt(st.nextToken());
+                if (map[r][c] == 1) {
+                    q.offer(new int[]{r, c});
+                    dist[r][c] = 0;
+                } else {
+                    dist[r][c] = -1;
+                }
+            }
+        }
+
+        while (!q.isEmpty()) {
+            int[] cur = q.poll();
+            int r = cur[0];
+            int c = cur[1];
+
+            for (int d = 0; d < 8; d++) {
+                int x = r + dx[d];
+                int y = c + dy[d];
+
+                if (x < 0 || x >= N || y < 0 || y >= M) continue;
+                if (dist[x][y] != -1) continue; // 이미 더 가까운 상어에서 방문됨
+
+                dist[x][y] = dist[r][c] + 1;
+                q.offer(new int[]{x, y});
+            }
+        }
+
+        int ans = 0;
+        for (int i = 0; i < N; i++) {
+            for (int j = 0; j < M; j++) {
+                if (dist[i][j] > ans) ans = dist[i][j];
+            }
+        }
+
+        System.out.println(ans);
+    }
+}