GATE | GATE CS 1997 | Question 52

[5-Marks question] 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.