백준 12100번 C++

#include <iostream>
#include <algorithm> 
#include <queue> 

using namespace std;
const int MAX = 21; 
int answer = 1;
int n; 
int board[MAX][MAX]; 

void moveblock(int k) { 
	switch (k) { 
	case 0: 
		for (int i = 0; i < n; i++) {
			queue<int> q;
			for (int j = n - 1; j >= 0; j--) {
				if (board[j][i] != 0)
					q.push(board[j][i]);
				board[j][i] = 0;
			}
			int index = n - 1;
			while (!q.empty()) {
				int value = q.front();
				q.pop();
				if (board[index][i] == 0)
					board[index][i] = value;
				else if (board[index][i] == value) {
					board[index][i] *= 2; 
					index--;
				}
				else {
					index--;
					board[index][i] = value;
				}
			}
		}
		break;
	case 1: 
		for (int i = 0; i < n; i++) {
		queue<int> q; 
		for (int j = 0; j < n; j++) { 
			if (board[j][i] != 0) 
				q.push(board[j][i]);
			board[j][i] = 0;
		}
		int index = 0;
		while (!q.empty()) { 
			int value = q.front(); 
			q.pop(); 
			if (board[index][i] == 0) 
				board[index][i] = value;
			else if (board[index][i] == value) {
				board[index][i] *= 2; 
				index++; 
			}
		else { 
			index++; 
			board[index][i] = value;
		}
		}
	}
		break; 
	case 2:
		for (int i = 0; i < n; i++) { 
			queue<int> q; 
			for (int j = n - 1; j >= 0; j--) {
				if (board[i][j] != 0) 
					q.push(board[i][j]);
				board[i][j] = 0; 
			} 
			int index = n - 1;
			while (!q.empty()) { 
				int value = q.front();
				q.pop();
				if (board[i][index] == 0) 
					board[i][index] = value;
				else if (board[i][index] == value) { 
					board[i][index] *= 2;
					index--;
				} 
				else { 
					index--;
					board[i][index] = value;
				}
			}
		}
		break; 
	case 3: 
		for (int i = 0; i < n; i++) { 
			queue<int> q; 
			for (int j = 0; j < n; j++) {
				if (board[i][j] != 0)
					q.push(board[i][j]);
				board[i][j] = 0; 
			} 
			int index = 0; 
			while (!q.empty()) {
				int value = q.front(); 
				q.pop(); 
				if (board[i][index] == 0) 
					board[i][index] = value;
				else if (board[i][index] == value) {
					board[i][index] *= 2;
					index++;
				}
				else {
					index++;
					board[i][index] = value;
				}
			}
		}
		break;
		}
}
 void dfs(int count) {
	 if (count == 5) {
		 for (int i = 0; i < n; i++) {
			 for (int j = 0; j < n; j++) {
				 answer = max(answer, board[i][j]);
			 }
		 }
		 return;
	 }
	 int copyboard[MAX][MAX];
	 for (int i = 0; i < n; i++) {
		 for (int j = 0; j < n; j++) {
			 copyboard[i][j] = board[i][j];
		 }
	 }
	 for (int k = 0; k < 4; k++) {
		 moveblock(k);
		 dfs(count + 1);
		 for (int i = 0; i < n; i++) {
			 for (int j = 0; j < n; j++) {
				 board[i][j] = copyboard[i][j];
			 }
		 }
	 }
 }
 int main(void) {
	 cin >> n;
	 for (int i = 0; i < n; i++) {
		 for (int j = 0; j < n; j++) {
			 cin >> board[i][j];
		 }
	 }
	 dfs(0);
	 cout << answer << endl;
	 return 0;
 }