#tensor-puzzles

Tensor Puzzle 2 asks for the sum of a vector without calling sum. What is s.shape?

def arange(i):
    return torch.tensor(range(i))

def ones(i):
    return arange(i) * 0 + 1

a = torch.tensor([3, 1, 4, 1])
s = a @ ones(4)[:, None]