task2

program p10n16;
{
  преобразовать математическое выражение в постфиксную форму
}
{$APPTYPE CONSOLE}

uses
  SysUtils, Windows,
  UStack in 'UStack.pas';

const
  leftBr = '(';
  rightBr = ')';
  operationsFirstPr = ['*', '/'];
  operationsSecondPr = ['-', '+'];
  operations = operationsFirstPr + operationsSecondPr;
  notOperands = [leftBr, rightBr] + operations;

var
  inp, answ, operand: String;
  ch: char;
  st: TStack;
  len, ind: integer;

procedure removeSpace(var s: string);
var
  ind, d, len: integer;
begin
  d:=0;
  for ind := 1 to length(s) do
    if s[ind]<>' ' then
      begin
        inc(d);
        s[d]:=s[ind]
      end;
  SetLength(s, d);
{

  ind := 1;
  d := 0;
  s := trim(s);
  len := length(s);
  while (ind + d <= len) do
  begin
    while (s[ind + d] = ' ') do
      inc(d);
    s[ind] := s[ind + d];
    inc(ind);
  end;
  Delete(s, len - d + 1, d);   }
end;

begin
  setConsoleOutputCP(1251);
  SetConsoleCP(1251);
  writeln('Введите исходную строку:');
  readln(inp);
  removeSpace(inp);
  answ := '';
  len := length(inp);
  ind := 1;
  while ind <= len do
  begin
    ch := inp[ind];
    if inp[ind] in notOperands then
    begin
      case ch of
        rightBr:
          begin
            while StackPeek(st) <> leftBr do
              answ := answ + StackPop(st) + ' ';
          end;
        '+', '-':
          begin
            while StackPeek(st) in operations do
              answ := answ + StackPop(st) + ' ';
          end;
        '*', '/':
          begin
            while StackPeek(st) in operationsFirstPr do
              answ := answ + StackPop(st) + ' ';
          end;
      end;
      if ch = rightBr then
        StackPop(st)
      else
        StackPush(st, ch);
    end
    else
    begin
      operand := ch;
      while (ind < len) and not(inp[ind + 1] in notOperands) do
      begin
        operand := operand + inp[ind + 1];
        inc(ind);
      end;
      answ := answ + operand + ' ';
    end;
    inc(ind);
  end;

  while not StackIsEmpty(st) do
    answ := answ + StackPop(st) + ' ';

  writeln(answ);
  readln;

end.




Unit UStack;

interface

const
  MaxN = 1000;

type
  TValue = char;
  TStackArray = array [1 .. MaxN] of TValue;

  TStack = record
    StackArray: TStackArray;
    top: integer;
  end;

procedure StackInit(var S: TStack);
procedure StackPush(var S: TStack; E: TValue);
function StackPop(var S: TStack): TValue;
function StackIsEmpty(var S: TStack): boolean;
function StackIsFull(var S: TStack): boolean;
function StackPeek(var S: TStack): TValue;

implementation

uses SysUtils;

procedure StackInit(var S: TStack);
begin
  S.top := 0;
end;

function StackIsEmpty(var S: TStack): boolean;
begin
  result := (S.top = 0);
end;

procedure StackPush(var S: TStack; E: TValue);
begin
  with S do
    if not StackIsFull(S) then
    begin
      inc(top);
      StackArray[top] := E;
    end
    else
      raise EOverflow.Create('Stack is full');
end;

function StackPop(var S: TStack): TValue;
begin
  with S do
    if top <> 0 then
    begin
      result := StackArray[top];
      dec(top);
    end
    else
      raise EUnderflow.Create('Stack is empty');
end;

function StackIsFull(var S: TStack): boolean;
begin
  result := (S.top = MaxN);
end;

function StackPeek(var S: TStack): TValue;
begin
  if S.top > 0 then
    result := S.StackArray[S.top];
end;

end.