(Dipindahkan dari note Facebook Program Pascal utk m’input data integer/karakter ke binary tree)

uses crt;

type
    tree = ^struct_tree;
    struct_tree = record
        ada_data: boolean;
        data: integer; (* kalo input data karakter, ganti jadi char *)
        kiri, kanan: tree;
    end;

var
    akar: tree;
    i, q: integer;
    input: integer; (* kalo input data karakter, ganti jadi char *)
    baru: tree;
    tmp: tree;
    cari: boolean;

(* kalo input data karakter, ganti n: integer jadi n: char *)
procedure insert_to_tree(n: integer; akar: tree);
begin
    if akar^.ada_data = false then
    begin
        akar^.data := n;
        akar^.ada_data := true;
    end
    else
    begin
        new(baru);
        baru^.ada_data := true;
        baru^.data := n;
        baru^.kiri := nil;
        baru^.kanan := nil;

        new(tmp);
        tmp := akar;
        cari := true;
        while cari do
        begin
            if input < tmp^.data then
            begin
                if tmp^.kiri = nil then
                begin
                    tmp^.kiri := baru;
                    tmp^.ada_data := true;
                    cari := false;
                end
                else
                begin
                    tmp := tmp^.kiri;
                end;
            end
            else
            begin
                if tmp^.kanan = nil then
                begin
                    tmp^.kanan := baru;
                    tmp^.ada_data := true;
                    cari := false;
                end
                else
                begin
                    tmp := tmp^.kanan;
                end;
            end;
        end;
    end;
end;

procedure tampil_preorder(node: tree);
begin
    if (node^.ada_data) then
    begin
        write(node^.data, ' ');
    end;

    if (node^.kiri nil) then
    begin
        tampil_preorder(node^.kiri);
    end;

    if (node^.kanan nil) then
    begin
        tampil_preorder(node^.kanan);
    end;
end;

procedure tampil_inorder(node: tree);
begin
    if (node^.kiri nil) then
    begin
        tampil_inorder(node^.kiri);
    end;

    if (node^.ada_data) then
    begin
        write(node^.data, ' ');
    end;

    if (node^.kanan nil) then
    begin
        tampil_inorder(node^.kanan);
    end;
end;

procedure tampil_postorder(node: tree);
begin
    if (node^.kiri nil) then
    begin
        tampil_postorder(node^.kiri);
    end;

    if (node^.kanan nil) then
    begin
        tampil_postorder(node^.kanan);
    end;

    if (node^.ada_data) then
    begin
        write(node^.data, ' ');
    end;
end;

begin
    clrscr;

    writeln('--[ tree ]--');

    (* inisialisasi akar pohon *)
    new(akar);
    akar^.ada_data := false;
    akar^.kiri := nil;
    akar^.kanan := nil;

    (* baca input Q, lalu lakukan perulangan sebanyak Q kali *)
    write('Q = '); readln(q);
    for i := 1 to q do
    begin
        write('integer ke-', i, ' = ');
        readln(input);

        insert_to_tree(input, akar);
    end;

    writeln;
    writeln;

    (* tampilkan secara preorder, inorder, postorder *);
    writeln('traverse secara pre-order');
    tampil_preorder(akar);

    writeln;
    writeln;

    writeln('traverse secara in-order');
    tampil_inorder(akar);

    writeln;
    writeln;

    writeln('traverse secara post-order');
    tampil_postorder(akar);

    writeln;
    writeln;

    writeln('Tekan ENTER untuk keluar . . . ');
    readln;
end.