ITPEC FE Subject B April 2026 Question 7

Topic: Array Manipulation

From the answer group below, select the correct combination of answers to be inserted into A and B in the program. Here, the array index starts at 1.

The function linearSearch linearly searches the global array D using the recursive function recursive, and if an element with the same value as the argument searchKey exists, it returns that element index, otherwise -1 is returned. Assume that the array D has no duplicate elements.

[Program]
global: integer []: D ← {3, 4, 2, 5, 9}
global: integer: N ← the number of elements of D
○ integer: linearSearch(integer: searchKey)
return recursive(searchKey, N)
○ integer: recursive(integer: searchKey, integer: index)
if (index < 1)
return -1
elseif (D[index] = searchKey)
return A
else
return recursive(searchKey, B)
endif

Answer group

OptionAB

Explanation

A: index, B: index - 1 — the recursion scans D from the last element down to the first, and on a match the current position is the answer.

  • •linearSearch starts the recursion with index = N = 5
  • •index < 1 means every element was checked without a hit, so −1 is returned
  • •a match at D[index] returns the position itself: A is index (printed Index in the answer group)
  • •otherwise the search moves one place left: B is index - 1

Trace for linearSearch(2) with D = {3, 4, 2, 5, 9}: D[5] is 9, D[4] is 5, D[3] is 2 and matches, so 3 is returned. For a missing key the calls reach index = 0 and return −1.

Answer (d)

Why not others:

  • •(a), (b) and (c) — return the constant 1 on a match, reporting position 1 wherever the value was found
  • •(g), (h) and (i) — return index - 1, one position before the element that matched
  • •(b), (e) and (h) — recurse with N - 1 every time, so only positions 5 and 4 are ever checked, and any other key recurses forever without reaching the base case
  • •(c), (f) and (i) — recurse with N - index: from 5 that is 0, so only D[5] is checked and every other key returns −1

Key rule: A recursive scan must pass a value derived from its own parameter, so that each call moves one step closer to the base case; a value built from a constant alone never moves.

Array Manipulation · AI-written, may contain errors

Practice this exam

This question comes from an official ITPEC past paper. ITPEC Practice is an independent study tool and is not affiliated with ITPEC. See the official FE past-paper collection or Report an issue.