C++ :
#include "iostream"

using namespace std;

int main()
{
    int n;
    double X1, Y1, X2, Y2;
    cin >> n >> X1 >> Y1 >> X2 >> Y2;

    double x1 = X1, y1 = Y1, x2 = X2, y2 = Y2, x3, y3, ans = 0;
    for(int i = 1; i <= n - 2; i++)
    {
        cin >> x3 >> y3;
        ans += x2 * (y3 - y1) + x3 * (y1 - y2) + x1 * (y2 - y3);
        x1 = x2; y1 = y2;
        x2 = x3; y2 = y3;
    }

    ans += x2 * (Y1 - y1) + X1 * (y1 - y2) + x1 * (y2 - Y1);
    x1 = x3; y1 = y3;
    x2 = X1; y2 = Y1;
    ans += x2 * (Y2 - y1) + X2 * (y1 - y2) + x1 * (y2 - Y2);

    ans > 0 ? cout << "ccw" : cout << "cw";
    return 0;
}

Pascal:

{$R-}

Var
  X, Y: Array[1..200002] Of Extended;
  i, n: LongInt;
  Ans: Extended;


  Function AL(Const x1, y1, x2, y2, x3, y3: Extended): Extended;
  Begin
    AL := x2 * (y3 - y1) + x3 * (y1 - y2) + x1 * (y2 - y3);
  End; { AL }


Begin
  ReadLn(n);
  For i := 1 To n Do
    ReadLn(X[i], Y[i]);
  X[n + 1] := X[1];
  Y[n + 1] := Y[1];

  X[n + 2] := X[2];
  Y[n + 2] := Y[2];

  ans := 0;
  For i := 1 To n Do
    ans := ans + AL(X[i], Y[i], X[i + 1], Y[i + 1], X[i + 2], Y[i + 2]);

  If ans < 0 Then
    Write('cw')
  Else
    Write('ccw');
End.




Edited by author 25.08.2010 18:34