In the following pseudocode, let $A$ be an array of $n$ positive integers, $x$ be a positive integer number, start be an index, $p$ be a list of integers, and result be a list of lists.

a$)$ Explain what the Mystery function does.

b$)$ Find an upper bound for its time complexity $(T).$ Hint: You need to write $T(n,x)$ as a recurrence relation and solve it by expanding it$.$

function func $(A,x)$ :

A$.$sort $()$

result $=[]$

Mystery $($A$,$ x$,0,[],$ result$)$

return result

function Mystery$($A$,x,$ start, $p,$ result$)$:

if $x==0$ :

result.append $(p)$

return

if $x<mn\; id="EditorElement\_4350557">0</mn>$ :

return

for i from start to $n-1$ :

$,$ result$)$