Question 10083 –

Let L = {a₁, a₂, ……, a_n} n ≥ 0 be a list whose Pascal representation is

                  type list = record
                     next: ↑ list; val: integer end  

The following function returns a list in which a_2i and a_2i-1, 1 ≤ i ≤ [n/2] are interchanged. Complete the function by filling the boxes. Write the line number and the content of the box in your answer sheet.

1. function change (p: ↑ list): ↑ list;
2. var q.t: ↑ list;
3. begin 
4. if p = nil then change := p
5. else if p ↑ next = nil then change : ▭
6. else begin
7. q : p ↑ next;
8. ▭ := q;
9. t : q ↑ next;
10. ▭ := p;
11. ▭ := change(t)
12. end
13. end 

Correct Answer: A