java数据结构实现机器人行走

import java.util.*; 
 
class FuShu 
{ 
 public double real; 
 public double image; 
  
 public FuShu() 
 { 
  real = 0; 
  image = 0; 
 } 
  
 public FuShu(double r, double i) 
 { 
  real = r; 
  image = i; 
 } 
  
 public FuShu dot(FuShu x) 
 { 
  FuShu r = new FuShu(); 
  r.real = real * x.real - image * x.image; 
  r.image = real * x.image + image * x.real; 
  return r; 
 } 
  
 public FuShu dot(double r, double i) 
 { 
  FuShu t = new FuShu(); 
  t.real = real * r - image * i; 
  t.image = real * i + image * r; 
  return t; 
 }  
} 
 
class Robot 
{ 
 private int x = 0; 
 private int y = 0; 
 private FuShu dir = new FuShu(1,0); 
  
 public void walk(String s) 
 { 
  int sum = 0; 
  for(int i=0; i<s.length(); i++) 
  { 
   char c = s.charAt(i); 
   if(c=='L' || c=='R') 
   { 
    x += sum * dir.real; 
    y += sum * dir.image; 
    sum = 0; 
    if(c=='L') 
     dir = dir.dot(0,1); 
    else 
     dir = dir.dot(0,-1); 
     
   } 
   else 
    sum = sum * 10 + (c-'0'); 
    
  } 
   
  x += sum * dir.real; 
  y += sum * dir.image;   
 } 
  
 public void show() 
 { 
  double d = Math.sqrt(x*x + y*y); 
  System.out.println(x+","+y + " dir: " + dir.real + "," + dir.image + ", d=" + d); 
 } 
} 
 
public class Walk 
{ 
 public static void main(String[] args) throws Exception 
 { 
  Robot t = new Robot(); 
  t.walk("3R4"); 
  t.show(); 
 } 
}