ITPEC FE Subject B April 2026 Question 1

1, 2 — trace the assignments in order, remembering that each one copies a current value.

Starting state: x = 1, y = 2, z = 3, ar = {0, 0}.

• •y ← x — y becomes 1 (the initial 2 is gone from here on)
• •ar[x] ← y — x is 1, so ar[1] becomes 1; array is now {1, 0}
• •z ← y — z becomes 1
• •x ← z — x becomes 1 (unchanged in effect)
• •ar[2] ← z + ar[1] — 1 + 1 = 2; array is now {1, 2}

Output: 1, 2

Answer (c)

Why not others:
- (a) 1, 0 — leaves ar[2] at its initial 0, skipping the last assignment
- (b) 1, 1 — computes z + ar[1] with the initial ar[1] of 0, missing that ar[1] was set to 1 two lines earlier
- (d) 2, 1, (e) 2, 2 and (f) 2, 3 — all begin with ar[1] = 2, which keeps the original y = 2 and ignores the very first assignment y ← x

Key rule: Write the variables down and update them line by line. Every option starting with 2 fails on the same slip, so getting y ← x right immediately halves the answer group.

AI-generated — may contain errors