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Q110FreeSystemVerilog

Remove duplicates while preserving order

Difficulty
Easy
Topic
Arrays
Language
SV
Interview prompt

Question

Remove duplicate integers from a sequence while preserving the first occurrence of every value in its original order.

Input sequence annotated as new or duplicate with blank stable-order output slots
Keep the first occurrence of each value and preserve the sequence's original order.
Candidate starting point

Implementation scaffold

function automatic void remove_duplicates(
  ref int in[$],
  ref int out[$]
);
  bit seen[int];
  int snapshot[$];
  // Implement here: keep first occurrences in encounter order.
endfunction
Reviewed example

Trace one case

Input
values=[3,1,3,2,1,4]
Expected output
[3,1,2,4]

Only the first occurrence of each integer is emitted, so the original encounter order is preserved.

What to cover

Requirements

  1. Clear any previous output.
  2. Emit a value only on its first appearance.
  3. Preserve first-occurrence ordering.
  4. The same queue variable may be passed as input and output; snapshot its original values before clearing output.
Continue practicing
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