[20250707] BOJ / G1 / 2048 (Easy) / 권혁준

Author: oncsr

khj20006/202507/07 BOJ G1 2048 (Easy).md

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+```java
+import java.util.*;
+import java.io.*;
+
+class IOController {
+    BufferedReader br;
+    BufferedWriter bw;
+    StringTokenizer st;
+
+    public IOController() {
+        br = new BufferedReader(new InputStreamReader(System.in));
+        bw = new BufferedWriter(new OutputStreamWriter(System.out));
+        st = new StringTokenizer("");
+    }
+
+    String nextLine() throws Exception {
+        String line = br.readLine();
+        st = new StringTokenizer(line);
+        return line;
+    }
+
+    String nextToken() throws Exception {
+        while (!st.hasMoreTokens()) nextLine();
+        return st.nextToken();
+    }
+
+    int nextInt() throws Exception {
+        return Integer.parseInt(nextToken());
+    }
+
+    long nextLong() throws Exception {
+        return Long.parseLong(nextToken());
+    }
+
+    double nextDouble() throws Exception {
+        return Double.parseDouble(nextToken());
+    }
+
+    void close() throws Exception {
+        bw.flush();
+        bw.close();
+    }
+
+    void write(String content) throws Exception {
+        bw.write(content);
+    }
+
+}
+
+public class Main {
+
+    static IOController io;
+
+    //
+
+    static int N;
+    static int[][] board;
+    static int ans = 0;
+    static String[] dirs = {"left", "right", "up", "down"};
+
+    public static void main(String[] args) throws Exception {
+
+        io = new IOController();
+
+        init();
+        solve();
+
+        io.close();
+
+    }
+
+    public static void init() throws Exception {
+
+        N = io.nextInt();
+        board = new int[N][N];
+        for(int i=0;i<N;i++) for(int j=0;j<N;j++) board[i][j] = io.nextInt();
+
+    }
+
+    static void solve() throws Exception {
+
+        backtracking(0);
+        io.write(ans + "\n");
+
+    }
+
+    static void backtracking(int turn) {
+
+        for(int i=0;i<N;i++) for(int j=0;j<N;j++) ans = Math.max(ans, board[i][j]);
+
+        if(turn >= 5) return;
+
+        for(String dir : dirs) {
+
+            int[][] copy = new int[N][N];
+            for(int i=0;i<N;i++) for(int j=0;j<N;j++) copy[i][j] = board[i][j];
+            move(dir);
+            backtracking(turn+1);
+            for(int i=0;i<N;i++) for(int j=0;j<N;j++) board[i][j] = copy[i][j];
+
+        }
+
+    }
+
+    static void move(String direction) {
+
+        if(direction.equals("left")) {
+            for(int i=0;i<N;i++) {
+                List<Integer> list = new ArrayList<>();
+                for(int j=0;j<N;j++) if(board[i][j] != 0) {
+                    list.add(board[i][j]);
+                }
+                List<Integer> newList = compress(list);
+                for(int j=0;j<N;j++) {
+                    board[i][j] = j >= newList.size() ? 0 : newList.get(j);
+                }
+            }
+        }
+        else if(direction.equals("right")) {
+            for(int i=0;i<N;i++) {
+                List<Integer> list = new ArrayList<>();
+                for(int j=N-1;j>=0;j--) if(board[i][j] != 0) {
+                    list.add(board[i][j]);
+                }
+                List<Integer> newList = compress(list);
+                for(int j=N-1;j>=0;j--) {
+                    board[i][j] = N-j > newList.size() ? 0 : newList.get(N-j-1);
+                }
+            }
+        }
+        else if(direction.equals("up")) {
+            for(int j=0;j<N;j++) {
+                List<Integer> list = new ArrayList<>();
+                for(int i=0;i<N;i++) if(board[i][j] != 0) {
+                    list.add(board[i][j]);
+                }
+                List<Integer> newList = compress(list);
+                for(int i=0;i<N;i++) {
+                    board[i][j] = i >= newList.size() ? 0 : newList.get(i);
+                }
+            }
+        }
+        else {
+            for(int j=0;j<N;j++) {
+                List<Integer> list = new ArrayList<>();
+                for(int i=N-1;i>=0;i--) if(board[i][j] != 0) {
+                    list.add(board[i][j]);
+                }
+                List<Integer> newList = compress(list);
+                for(int i=N-1;i>=0;i--) {
+                    board[i][j] = N-i > newList.size() ? 0 : newList.get(N-i-1);
+                }
+            }
+        }
+
+    }
+
+    static List<Integer> compress(List<Integer> list) {
+
+        List<Integer> newList = new ArrayList<>();
+        for(int j=0;j<list.size();j++) {
+            int prev = list.get(j);
+            if(j == list.size()-1) {
+                newList.add(prev);
+                break;
+            }
+            int next = list.get(j+1);
+            if(prev == next) {
+                newList.add(prev<<1);
+                j++;
+            }
+            else newList.add(prev);
+        }
+
+        return newList;
+
+    }
+
+}
+```