How do you write merge sort in Pascal?

Answer 1

To write a merge sort in Pascal, you need to implement a recursive function that divides the array into halves until single-element arrays are reached. Then, you merge these arrays back together in sorted order. Here's a basic structure:

procedure MergeSort(var arr: array of Integer; left, right: Integer);
var
  mid: Integer;
begin
  if left < right then
  begin
    mid := (left + right) div 2;
    MergeSort(arr, left, mid);
    MergeSort(arr, mid + 1, right);
    Merge(arr, left, mid, right); // You need to implement the Merge procedure
  end;
end;

You will also need to implement the Merge procedure to combine the sorted halves.