Question

How to extract the unique integers from an array excluding duplicates in Pascal

Answer 1

program UniqueExcludeDuplicatesProgram;

type
  TArray = array of Integer;
  TFrequencyMap = array of Integer;

function GetUniqueExcludeDuplicates(arr: TArray): TArray;
var
  frequency: TFrequencyMap;
  result: TArray;
  i, size, num: Integer;
begin
  // Initialize the frequency map
  SetLength(frequency, 1000); // Assuming values are within the range 0-999
  for i := 0 to High(frequency) do
    frequency[i] := 0;

  // Count frequencies of each number
  for i := 0 to High(arr) do
    Inc(frequency[arr[i]]);

  // Collect numbers that appear only once
  size := 0;
  for i := 0 to High(arr) do
  begin
    num := arr[i];
    if frequency[num] = 1 then
    begin
      SetLength(result, size + 1);
      result[size] := num;
      Inc(size);
    end;
  end;

  // Return the result array
  GetUniqueExcludeDuplicates := result;
end;

var
  arr, uniqueValues: TArray;
  i: Integer;
begin
  arr := TArray.Create(1, 2, 3, 5, 8, 3, 1, 1, 0, 6, 5, 7, 3, 1, 4, 9);

  uniqueValues := GetUniqueExcludeDuplicates(arr);

  Write('Unique values (excluding duplicates): ');
  for i := 0 to High(uniqueValues) do
  begin
    Write(uniqueValues[i], ' ');
  end;
  Writeln;
end.



(*
run:

Unique values (excluding duplicates): 2 8 0 6 7 4 9 

*)

 

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