ACM训练题（HDU - 1033）

HDU - 1033
For products that are wrapped in small packings it is necessary that the sheet of paper containing the directions for use is folded until its size becomes small enough. We assume that a sheet of paper is rectangular and only folded along lines parallel to its initially shorter edge. The act of folding along such a line, however, can be performed in two directions: either the surface on the top of the sheet is brought together, or the surface on its bottom. In both cases the two parts of the rectangle that are separated by the folding line are laid together neatly and we ignore any differences in thickness of the resulting folded sheet.

After several such folding steps have been performed we may unfold the sheet again and take a look at its longer edge holding the sheet so that it appears as a one-dimensional curve, actually a concatenation of line segments. If we move along this curve in a fixed direction we can classify every place where the sheet was folded as either type A meaning a clockwise turn or type V meaning a counter-clockwise turn. Given such a sequence of classifications, produce a drawing of the longer edge of the sheet assuming 90 degree turns at equidistant places.

Input
The input contains several test cases, each on a separate line. Each line contains a nonempty string of characters A and V describing the longer edge of the sheet. You may assume that the length of the string is less than 200. The input file terminates immediately after the last test case.

Output
For each test case generate a PostScript drawing of the edge with commands placed on separate lines. Start every drawing at the coordinates (300, 420) with the command “300 420 moveto”. The first turn occurs at (310, 420) using the command “310 420 lineto”. Continue with clockwise or counter-clockwise turns according to the input string, using a sequence of “x y lineto” commands with the appropriate coordinates. The turning points are separated at a distance of 10 units. Do not forget the end point of the edge and finish each test case by the commands stroke and showpage.

You may display such drawings with the gv PostScript interpreter, optionally after a conversion using the ps2ps utility.

Sample Input
V
AVV

Sample Output
300 420 moveto
310 420 lineto
310 430 lineto
stroke
showpage
300 420 moveto
310 420 lineto
310 410 lineto
320 410 lineto
320 420 lineto
stroke
showpage

题目简述：
一个物体在初始点（300，420），向x轴正方向前进，每次前进10，即（310，420）。
输入‘A ,’V‘，使该物体转向，A为顺时针转90度，V为逆时针转90度。每走一步输出一次当前物体所在的位置。

题目分析：
物体一共有四个方向可以去走，分别是上，下，左，右。所以我们需要定义四个不同的数去表示这样四个方向。每次走完我们都需要将方向转到当前标准，所以代表方向的变量是每次都是在变的，并且周期是4，即四个方向。

AC代码：

#include
#include
using namespace std;
int main()
{
 char s[500];
 int i;
 while (cin >> s)
 {
  int direct = 0,x=310,y=420;
  cout << 300 << " " << 420 << " " << "moveto" << endl;
  cout << 310 << " " << 420 << " " << "lineto" << endl;
  for (i = 0; i < strlen(s); i++)
  {
   if (s[i] == 'V')
   {
    switch (direct)
    {
    case 0:y += 10; break;
    case 1:x += 10; break;
    case 2:y -= 10; break;
    case 3:x -= 10; break;
    }
    direct = (direct + 3) % 4;
   }
   else
   {
    switch (direct)
    {
    case 0:y -= 10; break;
    case 1:x -= 10; break;
    case 2:y += 10; break;
    case 3:x += 10; break;
    }
    direct = (direct + 1) % 4;
   }
   cout << x << " " << y << " " << "lineto" << endl;
  }
  cout << "stroke" << endl;
  cout << "showpage" << endl;
 }
 return 0;
}