program MinOccurrenceExample;
{$mode objfpc}{$H+}
uses
SysUtils, Generics.Collections;
type
TIntArray = array of Integer;
// Function to find the element with minimum occurrences in an integer array
function FindMinOccurrence(const Arr: TIntArray; out MinElem: Integer): Boolean;
var
SortedArr: TIntArray;
I: Integer;
CurrentCount, MinCount: Integer;
begin
// Check for empty input array
if Length(Arr) = 0 then
Exit(False);
// 1. Create a copy of the original array to preserve source data
SetLength(SortedArr, Length(Arr));
for I := 0 to High(Arr) do
SortedArr[I] := Arr[I];
// 2. Sort using specialized TArrayHelper in Free Pascal
specialize TArrayHelper<Integer>.Sort(SortedArr);
// 3. Single pass to count consecutive runs
MinElem := SortedArr[0];
MinCount := Length(SortedArr) + 1; // Initialize higher than any possible count
CurrentCount := 1;
for I := 1 to Length(SortedArr) do
begin
// Check if current element matches previous element
if (I < Length(SortedArr)) and (SortedArr[I] = SortedArr[I - 1]) then
begin
Inc(CurrentCount);
end
else
begin
// Reached end of a group: update min tracker if count is smaller
if CurrentCount < MinCount then
begin
MinCount := CurrentCount;
MinElem := SortedArr[I - 1];
end;
CurrentCount := 1; // Reset count for next group
end;
end;
Result := True; // Success
end;
var
arr: TIntArray;
ResultVal: Integer;
begin
// Initialize the array
SetLength(arr, 15);
arr[0] := 1; arr[1] := 3; arr[2] := 1; arr[3] := 1; arr[4] := 4;
arr[5] := 4; arr[6] := 5; arr[7] := 5; arr[8] := 4; arr[9] := 2;
arr[10] := 2; arr[11] := 2; arr[12] := 3; arr[13] := 3; arr[14] := 3;
if FindMinOccurrence(arr, ResultVal) then
WriteLn(ResultVal) // Output: 5
else
WriteLn('Array is empty!');
end.
{
run:
5
}
