void printSpiral(A, int r, int c, int rows, int cols) {
    if(A == null || rows < 1 || cols < 1) {
        System.out.println();
        return;
    }
    if(rows == 1) {
        for(int i = 0; i < cols; i++)
            print(A[r][c+cols-1-i] + " ");
    } else if(cols == 1) {
        for(int i = 0; i < rows; i++) 
            print(A[r+rows-1-i][c] + " ");            
    } else {
        // print bounds
        for(int i = 0; i < rows-1; i++) 
            print(A[r+rows-1-i][c+cols-1] + " ");
        for(int i = 0; i < cols-1; i++)
            print(A[r][c+cols-1-i] + " ");
        for(int i = 0; i < rows-1; i++) 
            print(A[r+i][c] + " ");
        for(int i = 0; i < cols-1; i++)
            print(A[r+rows-1][c+i] + " ");
    }
    // recursive
    printSpiral(A, r+1, c+1, rows-2, cols-2);
}
    
def A = [
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9],
    [10, 11, 12],
];

def B = [
    [1, 2, 3],
    [4, 5, 6],
];

def C = [[1]];

def D = [
    [],
];

def E = [
    [1],
    [2],
    [3],
];

printSpiral(A, 0, 0, A.size, A[0].size);
printSpiral(B, 0, 0, B.size, B[0].size);
printSpiral(C, 0, 0, C.size, C[0].size);
printSpiral(D, 0, 0, D.size, D[0].size);
printSpiral(E, 0, 0, E.size, E[0].size);
printSpiral(null, -1, -1, 0, 0);