2048(Easy)

https://www.acmicpc.net/problem/12100

#include <iostream>

using namespace std;
int n;
int answer = 0;

struct BOARD {
	int map[20][20];

	void rotate() { //90도 회전
		int temp[20][20] = { 0 };
		for (int i = 0; i < n; i++) {
			for (int j = 0; j < n; j++) {
				temp[j][n-i-1] = map[i][j];
			}
		}
		for (int i = 0; i < n; i++) {
			for (int j = 0; j < n; j++) {
				map[i][j] = temp[i][j];
			}
		}
	}

	void up() { //위로 올리기
		int temp[20][20];
		for (int x = 0; x < n; x++) {
			int flag = 0; int target = -1;
			for (int y = 0; y < n; y++) {
				if (map[y][x] == 0) continue;
				if (flag == 1 && temp[target][x] == map[y][x]) {
					temp[target][x] *= 2;
					flag = 0;
				}
				else {
					temp[++target][x] = map[y][x];
					flag = 1;
				}
			}
			target++;
			for (; target < n; target++) {
				temp[target][x] = 0;
			}
		}
		for (int y = 0; y < n; y++) {
			for (int x = 0; x < n; x++) {
				map[y][x] = temp[y][x];
			}
		}
	}

	int get_max() {
		int result = 0;
		for (int y = 0; y < n; y++) {
			for (int x = 0; x < n; x++) {
				if (result < map[y][x]) result = map[y][x];
			}
		}
		return result;
	}
};

void dfs(BOARD cur, int count) {
	if (count == 5) {
		if (answer < cur.get_max()) { answer = cur.get_max(); }
		return;
	}
	for (int dir = 0; dir < 4; dir++) {
		BOARD next = cur;
		next.up();
		dfs(next, count + 1);
		cur.rotate();
	}
}

int main() {
	ios_base::sync_with_stdio(false);
	BOARD board;
	cin >> n;
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < n; j++) {
			cin >> board.map[i][j];
		}
	}
	dfs(board, 0);
	cout << answer << "\n";
	return 0;
}