BOJ_2468 : 안전 영역

Author: spring0913

week3/BOJ_2468(안전 영역).java

@@ -0,0 +1,62 @@
+import java.io.*;
+import java.util.*;
+
+public class Main {
+
+    public static int N;
+    public static int[][] map;
+    public static int[][] visited;
+
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        N = Integer.parseInt(br.readLine());
+        map = new int[N+1][N+1];
+        int max = Integer.MIN_VALUE;
+        for(int i=0; i<N; i++) {
+            StringTokenizer st = new StringTokenizer(br.readLine());
+            for(int j=0; j<N; j++) {
+                map[i][j] = Integer.parseInt(st.nextToken());
+                max = Math.max(max, map[i][j]);
+            }
+        }
+        int answer = 1;
+        for(int k=1; k<=max; k++) {
+            visited = new int[N+1][N+1];
+            int count = 0;
+            for(int i=0; i<N; i++) {
+                for(int j=0; j<N; j++) {
+                    if(visited[i][j] == 0 && map[i][j] > k) {
+                        count++;
+                        bfs(i, j, k, count);
+                    }
+                }
+            }
+            answer = Math.max(answer, count);
+        }
+        System.out.println(answer);
+    }
+
+    public static void bfs(int h, int w, int depth, int count) {
+        int[] dh = {-1, 0, 1, 0};
+        int[] dw = {0, 1, 0, -1};
+        Queue<int[]> q = new LinkedList<>();
+        q.offer(new int[]{h, w});
+        visited[h][w] = 1;
+        while(!q.isEmpty()) {
+            h = q.peek()[0];
+            w = q.peek()[1];
+            q.poll();
+
+            for(int i=0; i<4; i++) {
+                int nextH = h + dh[i];
+                int nextW = w + dw[i];
+                if(nextH >= 0 && nextH < N && nextW >= 0 && nextW < N) {
+                    if(visited[nextH][nextW] == 0 && map[nextH][nextW] > depth) {
+                        visited[nextH][nextW] = count;
+                        q.offer(new int[]{nextH, nextW});
+                    }
+                }
+            }
+        }
+    }
+}