program Records;

uses
    System.SysUtils, Math;

type
    PPolynomialNode = ^PolynomialNode;

    PolynomialNode = record
        Coefficient: Integer;
        Power: Integer;
        Next: PPolynomialNode;
    end;

procedure InputPolynomial(var p: PPolynomialNode);
var
    n, coef, pow: Integer;
    temp, last: PPolynomialNode;
begin
    Writeln('Input polynom power: ');
    ReadLn(n);
    last := nil;
    while (n >= 0) do
    begin
        Write('Input coefficient for variable with power ', n, ': ');
        ReadLn(coef);
        new(temp);
        temp^.Coefficient := coef;
        temp^.Power := n;
        temp^.Next := nil;
        if last = nil then
            p := temp
        else
            last^.Next := temp;
        last := temp;
        dec(n);
    end;
end;

function Equality(p, q: PPolynomialNode): Boolean;
begin

    while (p <> nil) and (q <> nil) do
    begin
        if (p^.Coefficient <> q^.Coefficient) or
          (p^.Power <> q^.Power) then
            exit(False);
        p := p^.Next;
        q := q^.Next;
    end;
    Result := (p = nil) and (q = nil);
end;

function Meaning(p: PPolynomialNode; x: Integer): Integer;
var
    sum, termValue: Integer;
begin
    sum := 0;

    while p <> nil do
    begin
        termValue := Round(p^.Coefficient * Power(x, p^.Power));
        sum := sum + termValue;

        p := p^.Next;
    end;

    Result := sum;
end;

procedure Add(p, q: PPolynomialNode; var r: PPolynomialNode);
var
    last, temp: PPolynomialNode;
begin
    new(r);
    last := r;
    while (p <> nil) and (q <> nil) do
    begin
        new(temp);
        if p^.Power > q^.Power then
        begin
            temp^ := p^;
            p := p^.Next;
        end
        else if q^.Power > p^.Power then
        begin
            temp^ := q^;
            q := q^.Next;
        end
        else
        begin
            temp^.Coefficient := p^.Coefficient + q^.Coefficient;
            temp^.Power := p^.Power;
            p := p^.Next;
            q := q^.Next;
        end;
        last^.Next := temp;
        last := temp;
    end;
    if p <> nil then
        last^.Next := p
    else
        last^.Next := q;
end;

procedure PrintPolynomial(p: PPolynomialNode);
var isFirstEl: boolean;
begin
    isFirstEl := true;
    while p <> nil do
    begin
        if (p^.Next <> nil) and (p^.Coefficient <> 0) and (isFirstEl = false) then
        begin
            Write(' + ', p^.Coefficient, 'x^', p^.Power)
        end
        else if (p^.Next = nil) and (p^.Coefficient <> 0) and (isFirstEl = false) then
            Write(' + ', p^.Coefficient, 'x^', p^.Power)
        else if (isFirstEl = true) and (p^.Coefficient <> 0) then
        begin
            Write(p^.Coefficient, 'x^', p^.Power);
            isFirstEl := false;
        end;
        p := p^.Next;
    end;
    WriteLn;
end;

var
    p, q, r: PPolynomialNode;
    x: Integer;

begin
    WriteLn('Input polynom p:');
    InputPolynomial(p);
    WriteLn('Input polynom q:');
    InputPolynomial(q);

    WriteLn('Polynom p: ');
    PrintPolynomial(p);
    WriteLn('Polynom q: ');
    PrintPolynomial(q);

    if Equality(p, q) then
        WriteLn('Polynoms are equal')
    else
        WriteLn('Polynoms are not equal');

    WriteLn('Input X value:');
    ReadLn(x);
    WriteLn('Polynom p value with x = ', x, ' equals ', Meaning(p, x));

    Add(p, q, r);

    Write('Sum of p and q: ');
    PrintPolynomial(r);
    ReadLn;

end.