POJ 1573 Robot Motion

模拟水题，Code:

#include<iostream>
 using namespace std;

struct Dir
{
    int y,x;
};
int main()
{
    const Dir dir[] = {{0, 1}, {1, 0}, {0, -1}, {-1, 0}};
    int M,N,E, vx, vy, step;
    char ch;
    char grid[10][10];
    while (cin >> M >> N >> E && (M*N*E))
    {
        int visit[10][10] = {0};

        for (int i = 0; i < M; i++)
        {
            for (int j = 0; j < N; j++)
            {
                cin >> ch;
                switch (ch)
                {
                case 'E':
                    grid[i][j] = 0;
                    break;
                case 'S':
                    grid[i][j] = 1;
                    break;
                case 'W':
                    grid[i][j] = 2;
                    break;
                default:
                    grid[i][j] = 3;
                }
            }
        }
        vx = E - 1, vy = 0;
        visit[vy][vx] = 1;
        step = 1;
        while (true)
        {
            int temp = grid[vy][vx];
            vy += dir[temp].y;
            vx += dir[temp].x;
            if (vy < 0 || vy >= M || vx < 0 || vx >= N)
            {
                cout << step << " step(s) to exit" << endl;
                break;
            }
            if (visit[vy][vx] != 0)
            {
                cout << visit[vy][vx] - 1<<" step(s) before a loop of "<<step -visit[vy][vx] + 1<< " step(s)" << endl;
                break;
            }
            else
                visit[vy][vx] = ++step;
        }
    }
    return 0;
}