spiral.py

spiral.py

def spiral(M, num_rows, num_cols):
    new_order = []
    # Corner indices of submatrices
    top = left = 0
    bottom, right = num_rows - 1, num_cols - 1

    while top <= bottom and left <= right:
        # Since you're sticking to one row/col, it's sufficient to use one iterator var
        for i in range(left, right + 1):
            new_order.append(M[top][i])
        top += 1
        for i in range(top, bottom + 1):
            new_order.append(M[i][right])
        right -= 1
        for i in range(right, left - 1, -1):
            new_order.append(M[bottom][i])
        bottom -= 1
        for i in range(bottom, top - 1, -1):
            new_order.append(M[i][left])
        left += 1

    return ' '.join(map(str, new_order))

if __name__ == "__main__":
    num_rows, num_cols = map(int, raw_input().strip().split(' '))
    M = []
    for _ in range(num_rows):
        M.append(map(int, raw_input().strip().split(' ')))
    print spiral(M, num_rows, num_cols)