[Beakjoon] 23-03-09

Baekjoon/hyeonjin/섬의_개수.java

@@ -0,0 +1,68 @@
+import java.io.*;
+import java.util.*;
+
+public class 섬의_개수 {
+    static int[] dx = {-1,-1,-1,0,0,1,1,1};
+    static int[] dy = {-1,0,1,-1,1,-1,0,1};
+    public static void main(String[] args) throws Exception{
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+        StringTokenizer str;
+
+        while(true){
+            str = new StringTokenizer(br.readLine());
+            int W = Integer.valueOf(str.nextToken());
+            int H = Integer.valueOf(str.nextToken());
+            if(W == 0 && H == 0) break;
+
+            int[][] arr = new int[H][W];
+            boolean[][] check = new boolean[H][W];
+            for(int i = 0; i < H; i++){
+                str = new StringTokenizer(br.readLine());
+                for(int j = 0; j < W; j++){
+                    arr[i][j] = Integer.valueOf(str.nextToken());
+                }
+            }
+
+            int cnt = 0;
+            for(int i = 0; i < H; i++){
+                for(int j = 0; j < W; j++){
+                    if(check[i][j] || arr[i][j] == 0) continue;
+
+                    cnt++;
+                    Queue<Point> queue = new LinkedList<>();
+                    queue.add(new Point(i,j));
+                    check[i][j] = true;
+
+                    while(!queue.isEmpty()){
+                        Point p = queue.poll();
+                        for(int k = 0; k < 8; k++){
+                            int x = p.x + dx[k];
+                            int y = p.y + dy[k];
+
+                            if(x < 0 || x >= H || y < 0 || y >= W || check[x][y] || arr[x][y] == 0) continue;
+
+                            queue.add(new Point(x,y));
+                            check[x][y] = true;
+                        }
+                    }
+                }
+            }
+            bw.write(String.valueOf(cnt));
+            bw.newLine();
+        }
+
+        bw.flush();
+        bw.close();
+    }
+
+    public static class Point{
+        int x;
+        int y;
+
+        public Point(int x, int y){
+            this.x = x;
+            this.y = y;
+        }
+    }
+}

Baekjoon/hyeonjin/시간_여행.java

@@ -0,0 +1,44 @@
+import java.io.*;
+import java.util.*;
+
+public class 시간_여행 {
+    static Stack<Integer>[] array;
+    static Stack<Integer> stack;
+    public static void main(String[] args) throws Exception{
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+        StringTokenizer str;
+
+        int N = Integer.valueOf(br.readLine());
+
+        array = new Stack[N + 1];
+        array[0] = new Stack<>();
+        stack = new Stack<>();
+
+        for(int i = 1; i <= N; i++){
+            str = new StringTokenizer(br.readLine());
+            switch (str.nextToken().charAt(0)){
+                case 'a':
+                    stack.add(Integer.valueOf(str.nextToken()));
+                    break;
+
+                case 's':
+                    stack.pop();
+                    break;
+
+                case 't':
+                    stack.clear();
+                    stack.addAll(array[Integer.valueOf(str.nextToken()) - 1]);
+                    break;
+            }
+
+            array[i] = new Stack<>();
+            array[i].addAll(stack);
+            if(stack.isEmpty()) bw.write("-1");
+            else bw.write(String.valueOf(stack.peek()));
+            bw.newLine();
+        }
+        bw.flush();
+        bw.close();
+    }
+}