模板

1、螺旋矩阵求值（右上为1，往下走）

long long f(long long n,long long x,long long y){
    x = n - x + 1;
    y = n - y + 1;
    long long  r = 0;
    if(x <= y & x + y <= n+1)
    {
        r = x;
        return  4*(r-1)*n - 4*(r-1)*(r-1) +1 + y-r;
    }
    if(x<=y & x+y >= n+1)
    {
        r = n- y + 1;
        return 4*(r-1)*n - 4*(r-1)*(r-1) + 1 + n-2*r + 1 + x - r;
    }
    if(x>=y & x+y >= n+1)
    {
        r = n - x +1;
        return 4*(r-1)*n - 4*(r-1)*(r-1) + 1 + 3*n-6*r + 3 - y + r;
    }
    if(x>=y & x+y <= n+1)
    {
        r = y;
        return 4*(r-1)*n - 4*(r-1)*(r-1) + 1 + 4*n-8*r + 4  - x + r;
    }
    return 0;
}