[삼성 SW 역량 테스트] 뱀

#include <stdio.h>

int n, k, m;
int map[101][101];

int head_y, head_x, tail_index;
int snake_y[10101], snake_x[10101];
char cmd[10001];

const int dy[] = { 0, +1, 0, -1 };
const int dx[] = { +1, 0, -1, 0 };

int main()
{
	scanf("%d %d", &n, &k);

	int y, x;
	for (int i = 0; i < k; ++i) {
		scanf("%d %d", &y, &x);
		map[y][x] = 1;
	}

	int time;
	char c;
	scanf("%d", &m);
	for (int i = 0; i < m; ++i) {
		scanf("%d %c", &time, &c);
		cmd[time] = c;
	}

	int dir = 0;
	time = 0;
	head_y = 1, head_x = 1, tail_index = time;
	snake_y[time] = head_y, snake_x[time] = head_x;
	map[head_y][head_x] = -1;

	while (true) {
		++time;

		head_y += dy[dir];
		head_x += dx[dir];

		if (head_y < 1 || head_y > n || head_x < 1 || head_x > n || map[head_y][head_x] == -1) {
			break;
		}

		snake_y[time] = head_y;
		snake_x[time] = head_x;
		if (map[head_y][head_x] == 0) {
			int tail_y = snake_y[tail_index];
			int tail_x = snake_x[tail_index];
			map[tail_y][tail_x] = 0;
			++tail_index;
		}
		map[head_y][head_x] = -1;

		if (cmd[time] == 'D') {
			dir = (dir + 1) % 4;
		}

		if (cmd[time] == 'L') {
			dir = (dir + 3) % 4;
		}
	}

	printf("%d\n", time);
	
	return 0;
}