Q$18$: Banded matrices

Construct an upper triangular matrix $Uin{R}^{nn}$ with upper bandwidth $p.$ The non$-$zero entries should be alternating between $1$ and $-1$ in each row, with the diagonal entries equal to $1.$

rng$(18)$; $n=$ randi $([2040])$ ; p$=$randi $(10)$;

$\%$Edit the line below to generate the banded matrix