蛇形矩阵(数组模拟方向， d代表转弯)

• 蛇形矩阵
  

#include <iostream>

using namespace std;

const int N = 110;

int n, m;
int q[N][N];

int main()
{
    
    cin >> n >> m;
    int dx[] = {
    -1, 0, 1, 0}, dy[] = {
    0, 1, 0, -1};
    int x = 0, y = 0, d = 1;
    for (int i = 1; i <= n * m; i ++ )
    {
    
        q[x][y] = i;
        int a = x + dx[d], b = y + dy[d];
        if (a < 0 || a >= n || b < 0 || b >= m || q[a][b])
        {
    
            d = (d + 1) % 4;
            a = x + dx[d], b = y + dy[d];
        }
        x = a, y = b;
    }

    for (int i = 0; i < n; i ++ )
    {
    
        for (int j = 0; j < m; j ++ )
            cout << q[i][j] << ' ';
        cout << endl;
    }

    return 0;
}

撞墙代表着出界或者已经走过了 ，d代表什么时候转弯；