ITPEC FE Subject B April 2026 Question 1

Topic: Array Manipulation

From the answer group below, select the correct answer to be inserted into blank in the description. Here, the array index starts at 1.

When the program is executed, the output is “blank”.

[Program]
integer: x ← 1
integer: y ← 2
integer: z ← 3
integer []: ar ← {0, 0}
y ← x
ar[x] ← y
z ← y
x ← z
ar[2] ← z + ar[1]
output ar[1], ar[2] // the values are separated by ", "

Answer group

Explanation

1, 2 — trace the assignments in order; each one copies the value its right-hand side holds at that moment.

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

  • •y ← x — y becomes 1, and the initial 2 is gone from here on
  • •ar[x] ← y — x is 1, so ar[1] becomes 1 and the array is {1, 0}
  • •z ← y — z becomes 1
  • •x ← z — x stays 1
  • •ar[2] ← z + ar[1] — 1 + 1 = 2, so the array is {1, 2}

The output is 1, 2.

Answer (c)

Why not others:

  • •(a) 1, 0 — leaves ar[2] at its initial 0, skipping the last assignment
  • •(b) 1, 1 — adds the initial ar[1] of 0 to z, missing that ar[1] was set to 1 two lines earlier
  • •(d) 2, 1, (e) 2, 2 and (f) 2, 3 — start with ar[1] = 2, which keeps the original y = 2 and ignores the first assignment y ← x

Key rule: Keep a table of the variables and update it line by line; an assignment copies a value once and does not link the two variables afterwards.

Array Manipulation · AI-written, may contain errors

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