Google 编程竞赛题

Problem Statement
When editing a single line of text, there are four keys that can be used to move the cursor: end, home, left-arrow and right-arrow. As you would expect, left-arrow and right-arrow move the cursor one character left or one character right, unless the cursor is at the beginning of the line or the end of the line, respectively, in which case the keystrokes do nothing (the cursor does not wrap to the previous or next line). The home key moves the cursor to the beginning of the line, and the end key moves the cursor to the end of the line.  You will be given a int, N, representing the number of character in a line of text. The cursor is always between two adjacent characters, at the beginning of the line, or at the end of the line. It starts before the first character, at position 0. The position after the last character on the line is position N. You should simulate a series of keystrokes and return the final position of the cursor. You will be given a String where characters of the String represent the keystrokes made, in order. 'L' and 'R' represent left and right, while 'H' and 'E' represent home and end.
Definition
   
Class:
CursorPosition
Method:
getPosition
Parameters:
String, int
Returns:
int
Method signature:
int getPosition(String keystrokes, int N)
(be sure your method is public)
   
Constraints

keystrokes will be contain between 1 and 50 'L', 'R', 'H', and 'E' characters, inclusive.

N will be between 1 and 100, inclusive.
Examples
0)
   
"ERLLL"
10
Returns: 7
First, we go to the end of the line at position 10. Then, the right-arrow does nothing because we are already at the end of the line. Finally, three left-arrows brings us to position 7.
1)
   
"EHHEEHLLLLRRRRRR"
2
Returns: 2
All the right-arrows at the end ensure that we end up at the end of the line.
2)
   
"ELLLELLRRRRLRLRLLLRLLLRLLLLRLLRRRL"
10
Returns: 3
3)
   
"RRLEERLLLLRLLRLRRRLRLRLRLRLLLLL"
19
Returns: 12

我的java实现

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class CursorPosition {
 
 //private int n;
 //private String keystrokes;
 private int Returns;
 /**
  * @param args
  */
 public int getPosition(String keystrokes,int n){
  Returns=n;
  for (int i=0;i<keystrokes.length();i++){
   switch(keystrokes.charAt(i)){
   case 'H':
    Returns=0;break;
   case 'E':
    //System.out.println("ok");
    Returns=n;break;
   case 'L':
    if (Returns>0)
    Returns--;
    break;
   case 'R':
    if (Returns<n)
    Returns++;
    break;
   default:
    //System.out.println(keystrokes.charAt(i));
    System.out.println("err:keystrokes");
    break;
   }
  }
  return Returns;
 }
 public static void main(String[] args) throws IOException {
  // TODO Auto-generated method stub
  BufferedReader in=new BufferedReader(new InputStreamReader(System.in));
  String keystrokes;
  int n,Returns;
  System.out.println("input keystrokes:");
  keystrokes=in.readLine();
  System.out.println("input N:");
  n=Integer.parseInt(in.readLine());

  CursorPosition cp=new CursorPosition ();
  Returns=cp.getPosition(keystrokes,n);
  System.out.println("Returns="+Returns);
 }

}