[20250627] BOJ / P4 / 2048 (Hard) / 설진영

Author: Seol-JY

Seol-JY/202506/27 BOJ P4 2048 (Hard).md

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+```java
+import java.io.BufferedReader;
+import java.io.InputStreamReader;
+import java.util.StringTokenizer;
+
+public class Main {
+    
+    static int n, answer;
+    static int[][] map;
+    
+    public static void main(String[] args) throws Exception {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        n = Integer.parseInt(br.readLine());
+        answer = 0;
+        map = new int[n][n];
+        
+        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());
+            }
+        }
+        
+        game(0);
+        System.out.println(answer);
+    }
+    
+    public static void game(int count) {
+        if (count == 10) {
+            findMax();
+            return;
+        }
+        
+        int currentMax = getCurrentMax();
+        if (currentMax * (1 << (10 - count)) <= answer) {
+            return;
+        }
+        
+        int[][] backup = new int[n][n];
+        for (int i = 0; i < n; i++) {
+            backup[i] = map[i].clone();
+        }
+        
+        for (int dir = 0; dir < 4; dir++) {
+            move(dir);
+            game(count + 1);
+            
+            for (int i = 0; i < n; i++) {
+                map[i] = backup[i].clone();
+            }
+        }
+    }
+    
+    public static void move(int dir) {
+        if (dir == 0) {
+            for (int j = 0; j < n; j++) {
+                int index = 0;
+                int prev = 0;
+                for (int i = 0; i < n; i++) {
+                    if (map[i][j] != 0) {
+                        if (prev == map[i][j]) {
+                            map[index - 1][j] = prev * 2;
+                            prev = 0;
+                        } else {
+                            prev = map[i][j];
+                            map[index][j] = prev;
+                            index++;
+                        }
+                        if (i != index - 1) map[i][j] = 0;
+                    }
+                }
+            }
+        } else if (dir == 1) {
+            for (int j = 0; j < n; j++) {
+                int index = n - 1;
+                int prev = 0;
+                for (int i = n - 1; i >= 0; i--) {
+                    if (map[i][j] != 0) {
+                        if (prev == map[i][j]) {
+                            map[index + 1][j] = prev * 2;
+                            prev = 0;
+                        } else {
+                            prev = map[i][j];
+                            map[index][j] = prev;
+                            index--;
+                        }
+                        if (i != index + 1) map[i][j] = 0;
+                    }
+                }
+            }
+        } else if (dir == 2) {
+            for (int i = 0; i < n; i++) {
+                int index = 0;
+                int prev = 0;
+                for (int j = 0; j < n; j++) {
+                    if (map[i][j] != 0) {
+                        if (prev == map[i][j]) {
+                            map[i][index - 1] = prev * 2;
+                            prev = 0;
+                        } else {
+                            prev = map[i][j];
+                            map[i][index] = prev;
+                            index++;
+                        }
+                        if (j != index - 1) map[i][j] = 0;
+                    }
+                }
+            }
+        } else {
+            for (int i = 0; i < n; i++) {
+                int index = n - 1;
+                int prev = 0;
+                for (int j = n - 1; j >= 0; j--) {
+                    if (map[i][j] != 0) {
+                        if (prev == map[i][j]) {
+                            map[i][index + 1] = prev * 2;
+                            prev = 0;
+                        } else {
+                            prev = map[i][j];
+                            map[i][index] = prev;
+                            index--;
+                        }
+                        if (j != index + 1) map[i][j] = 0;
+                    }
+                }
+            }
+        }
+    }
+    
+    public static void findMax() {
+        for (int i = 0; i < n; i++) {
+            for (int j = 0; j < n; j++) {
+                answer = Math.max(answer, map[i][j]);
+            }
+        }
+    }
+    
+    public static int getCurrentMax() {
+        int max = 0;
+        for (int i = 0; i < n; i++) {
+            for (int j = 0; j < n; j++) {
+                max = Math.max(max, map[i][j]);
+            }
+        }
+        return max;
+    }
+}
+```