Get n numbers from a list

I know there is a function nchoosek, however is there any way to do this without using this particular command since we aren't allowed to use it yet?

For example, [1,2,3,4] and we need to take 3 numbers at time. The results should be [1 2 3] [1 2 4] [1 3 4] [2 3 4]

Answer 1

[Dyuman Joshi]

Binary approach (however, it might get slow for large numbers of element in x)

%vectorized method of this approach might be a little faster

x=[1 2 3 4];
y=[];
for i=1:2^numel(x)-1
    if nnz(dec2bin(i,numel(x))=='1')==3
        y=[x(dec2bin(i,numel(x))=='1'); y];
    end
end
y

y = 4×3

1 2 3 1 2 4 1 3 4 2 3 4