1. 소스 1 : 2학년때 자료구조 숙제로 작성 (약간 Iterative한것 같다) ¶
~cpp 
#include <iostream>
#include <ctime>
#include <cstdlib>
using namespace std;
// move direction and board.
int	 direction_x[]={-1,0,1,1,1,0,-1,-1};
int	 direction_y[]={1,1,1,0,-1,-1,-1,0};
int	 board[40][20];	// maximum size of the board is : 40x20
// required variables.
int	 sizeX, sizeY, xPos, yPos, NumOfBlock, loop=0;
const int DIRECTION = 8;
void input();
void output();
void move();
void init_board();
int main()
{
         init_board();
	input();
	move();
	output();
	
	return 0;
}
void init_board()
{
	for(int i=0; i<sizeX; i++)
		for(int j=0; j<sizeY; j++)
			board[i][j]=0;
}
void move()
{
	int k;
	srand((unsigned)time(NULL));
	// initial point
	board[xPos][yPos]++;
         NumOfBlock--;
	// move roach while loop is smaller than 50,000
	while(loop<50000)
	{
		k = rand()%DIRECTION;
		// prevent the roach moves outside of the board
		if(xPos+direction_x[k]<0 || xPos+direction_x[k]>sizeX-1
			|| yPos+direction_y[k]<0 || yPos+direction_y[k]>sizeY-1)
			continue;
		xPos += direction_x[k];
		yPos += direction_y[k];
		if(board[xPos][yPos]==0)
			NumOfBlock--;
		board[xPos][yPos]++;
		
		if(NumOfBlock==0)
			break;
		loop++;
	}
}
void input()
{
	cout << "input size of the board" << endl;
	while(cin >> sizeX >> sizeY)
	{
		if(sizeX>40 || sizeY>20)
		{
			cout << "size is out of range.\ntry again.";
			continue;
		}
		break;
	}
	NumOfBlock=sizeX*sizeY;
	cout << "input start point;" << endl;
	while(cin >> xPos >> yPos)
	{
		if(xPos>40 || yPos>20)
		{
			cout << "point is out of range.\ntry again.";
			continue;
		}
		break;
	}
}
void output()
{
	int i,j;
	// print outputs.
	for(i=0; i<sizeX; i++)
	{
		for(j=0; j<sizeY; j++)
		{
			cout.width(4);
			cout << board[i][j];
			if(j==sizeY-1)
				cout << endl;
		}
	}
	cout << "loop : " << loop << " times" << endl;
}
 
2. 소스 2 : 1에 STL을 사용하고 약간의 Refactoring ¶
~cpp 
#include <iostream>
#include <ctime>
#include <vector>
using namespace std;
#define DIRECTION 8
// move direction and board.
int	 direction_x[]={-1,0,1,1,1,0,-1,-1};
int	 direction_y[]={1,1,1,0,-1,-1,-1,0};
int sizeX, sizeY;
int NumberOfUnvisitedBlocks = 0, LoopCount= 0 ;
vector<vector<int> > board;
void printOutResult();
void moveRoach(int x, int y);
int main()
{
	cout << "Size of the board : ";
	cin >> sizeX >> sizeY;
	NumberOfUnvisitedBlocks = sizeX * sizeY;
	// initizlize the vector
	board.resize(sizeX);
	vector<vector<int> >::iterator iter;
	for(iter=board.begin(); iter!=board.end(); ++iter)
		(*iter).resize(sizeY);
	cout << "Starting Point : ";
	int xPos, yPos;
    cin >> xPos >> yPos;
    
	moveRoach(xPos, yPos);
	
	printOutResult();
	return 0;
}
void moveRoach(int xPos, int yPos)
{
	int k;
	srand((unsigned)time(NULL));
	// initial point
	board[xPos][yPos]++;
	NumberOfUnvisitedBlocks--;
	// move roach while 'loop' is smaller than 50,000
	while(LoopCount<50000)
	{
		k = rand()%DIRECTION;
		// prevent the roach moves outside of the board
		if(xPos+direction_x[k]<0 || xPos+direction_x[k]>sizeX-1
			|| yPos+direction_y[k]<0 || yPos+direction_y[k]>sizeY-1)
			continue;
		xPos += direction_x[k];
		yPos += direction_y[k];
		if(board[xPos][yPos]==0)
			NumberOfUnvisitedBlocks--;
		board[xPos][yPos]++;
		if(NumberOfUnvisitedBlocks==0)
			break;
		
		LoopCount++;
	}
}
void printOutResult()
{
	int i,j;
	// print outputs.
	for(i=0; i<sizeX; i++)
	{
		for(j=0; j<sizeY; j++)
		{
			cout.width(4);
			cout << board[i][j];
		}
		cout << endl;
	}
	cout << "Total : " << LoopCount << " times repeated " << endl;
}
 
3. 소스 3 : Recursion 을 이용해봄 ¶
~cpp 
#include <iostream>
#include <vector>
#include <ctime>
using namespace std;
#define NUMOFDIRECTIONS 8
typedef vector<vector<int> > Board;
Board roachJourney;
int	 dir_x[]={-1,0,1,1,1,0,-1,-1};
int	 dir_y[]={1,1,1,0,-1,-1,-1,0};
int sizeX, sizeY;
void moveRoachRecursively(int dirIdx);
void printOutResult();
int main()
{
	cout << "Size of the board : ";
	cin >> sizeX >> sizeY;
	roachJourney.resize(sizeX);
	Board::iterator iter;
	for(iter=roachJourney.begin(); iter!=roachJourney.end(); ++iter)
		(*iter).resize(sizeY);
	moveRoachRecursively(rand()%NUMOFDIRECTIONS);
	printOutResult();
	return 0;
}
void moveRoachRecursively(int dirIdx)
{
	// starting point is 0,0
	// i'm not sure that this is an excessive use of 'static' keyword
	static int posX = 0, posY = 0;
    static int numOfUnVstdPlces = sizeX*sizeY;
	
	// if the roach moved outside of the board ignore that case.
	if(! (posX+dir_x[dirIdx]<0 || posX+dir_x[dirIdx]>sizeX-1
		|| posY+dir_y[dirIdx]<0 || posY+dir_y[dirIdx]>sizeY-1) )
	{
		posX += dir_x[dirIdx];
		posY += dir_y[dirIdx];
		if( roachJourney[posX][posY] == 0 )
			numOfUnVstdPlces--;
		roachJourney[posX][posY]++;
	}
    
	if( numOfUnVstdPlces != 0) // choose next direction
        moveRoachRecursively((unsigned)(rand())%NUMOFDIRECTIONS);
	else
		return;
}
void printOutResult()
{
	Board::iterator iterX;
	for(iterX=roachJourney.begin(); iterX!=roachJourney.end(); ++iterX)
	{
		vector<int>::iterator iterY;
		for(iterY=(*iterX).begin(); iterY!=(*iterX).end(); ++iterY)
		{
			cout.width(4);
			cout << (*iterY);
		}
		cout << endl;
	}
}
 
4. 소스 4 : OO 적으로 ¶
- 별로 OO 적이지 못한것 같다...(Roach 와 Board 객체가 양방향참조를 한다). DesignPatterns 를 참고하면서 보았어야 하는데.. 나중에 Refactoring 해야 함..
- ~cpp Roach.java
 - ~cpp import java.util.Random; public class Roach{ int dir_x[]={-1,0,1,1,1,0,-1,-1}; int dir_y[]={1,1,1,0,-1,-1,-1,0}; Board _board; boolean bOnTrip; Random rand; public Roach() { bOnTrip = true; rand = new Random(); } public void move() { int randNum; while( bOnTrip ) { randNum = rand.nextInt()%dir_x.length; try { _board.walkOn(dir_x[randNum], dir_y[randNum]); } catch (ArrayIndexOutOfBoundsException e) { //System.err.println(e); drink(); } } } public void finishJourney() { bOnTrip = false; } public void drink() { System.out.println("toast~!"); } public void putOnTheBoard(Board board) { _board = board; } }
- ~cpp Board.java
 - ~cpp public class Board { int _board[][]; int sizeX, sizeY; int roaX, roaY; // watch position of the roach // because the roach doesn't know his position int visitedPlace = 1; Roach _roach; public Board(int x, int y) { sizeX = x; sizeY = y; roaX = roaY = 0; _board = new int[sizeX][sizeY]; } public void walkOn(int x, int y) { System.out.println("바퀴위치 : " + (roaX+x) + ", " + (roaY+y)); if ( _board[roaX+x][roaY+y] == 0 ) visitedPlace++; roaX += x; roaY += y; System.out.println("바퀴위치 : " + roaX + ", " + roaY); _board[roaX][roaY]++; if( visitedPlace == sizeX*sizeY ) { _roach.finishJourney(); printOutBoard(); } } public void putRoachOn(Roach roach) { _roach = roach; } public void printOutBoard() { for(int i=0; i<sizeX; i++) { for(int j=0; j<sizeY; j++) { System.out.print(_board[i][j] + "\t"); } System.out.println(); } } }
- ~cpp RandomWalk.java
 - ~cpp public class RandomWalk { public static void main(String[] args){ Roach myRoach = new Roach(); Board myBoard = new Board(8,8); myRoach.putOnTheBoard(myBoard); myBoard.putRoachOn(myRoach); myRoach.move(); } }
5. 소스 5 : 재미있을것 같은 CSP ¶
TokenRing 에서 아이디어를 얻어 나름대로 만들어봤는데 (아직 제대로 동작하는지 미확인. 이 글을 작성하는 도중에도 버그가 하나둘 보이고 BadSmell 이 많이 난다. PC가 많은 곳에서 추가작업필요...  ) 이게 CSP 의 이념에 부합하는지 모르겠다. m by n 배열에 있는 셀들을 TokenRingNetwork 형태를 띠게 하면서 사실은 배열인것처럼 동작하게 했다. 이 방법 말고 마땅한 방법이 떠오르지 않았다. TestDrivenDevelopment 으로 작성해보려고 했지만 실천에 옮기지 못했다. 몸에 밴 습관이란건 극복하기가 쉽지 않은 것 같다.
 ) 이게 CSP 의 이념에 부합하는지 모르겠다. m by n 배열에 있는 셀들을 TokenRingNetwork 형태를 띠게 하면서 사실은 배열인것처럼 동작하게 했다. 이 방법 말고 마땅한 방법이 떠오르지 않았다. TestDrivenDevelopment 으로 작성해보려고 했지만 실천에 옮기지 못했다. 몸에 밴 습관이란건 극복하기가 쉽지 않은 것 같다.
 ) 이게 CSP 의 이념에 부합하는지 모르겠다. m by n 배열에 있는 셀들을 TokenRingNetwork 형태를 띠게 하면서 사실은 배열인것처럼 동작하게 했다. 이 방법 말고 마땅한 방법이 떠오르지 않았다. TestDrivenDevelopment 으로 작성해보려고 했지만 실천에 옮기지 못했다. 몸에 밴 습관이란건 극복하기가 쉽지 않은 것 같다.
 ) 이게 CSP 의 이념에 부합하는지 모르겠다. m by n 배열에 있는 셀들을 TokenRingNetwork 형태를 띠게 하면서 사실은 배열인것처럼 동작하게 했다. 이 방법 말고 마땅한 방법이 떠오르지 않았다. TestDrivenDevelopment 으로 작성해보려고 했지만 실천에 옮기지 못했다. 몸에 밴 습관이란건 극복하기가 쉽지 않은 것 같다.- Cell.java
 ~cpp /** * Created by IntelliJ IDEA. * Author: Intaek Lim * Date: 2003. 6. 7. * Time: 오후 10:29:36 */ import java.net.*; import java.io.*; import java.util.Random; // operates just like 'token ring' public class Cell implements Runnable { private String _nextHostName, _localHostName; private int _hostIndex, _nextHostIndex; private int _numOfVisited; private int _xSize, _ySize; private int _adjacentCellIdx[]; private ServerSocket _serverSock; private Socket _nextSock; private final int _defaultPort = 38317; private boolean _bEndCondition; public Cell(int localHostNum, int hostIndex, String nextHostName, int nextHostNum) { _hostIndex = localHostNum; _hostIndex = hostIndex; _bEndCondition = false; try { _serverSock = new ServerSocket(_defaultPort); } catch(IOException e) { System.err.println(e); } } public void setXY(int x, int y) { _xSize = x; _ySize = y; } public void setAdjacentCells(String adjIdx) { // parse adjacent cell info String adjHostIdxes[] = adjIdx.split(" "); _adjacentCellIdx = new int[adjHostIdxes.length]; for(int i=0; i<_adjacentCellIdx.length; i++) _adjacentCellIdx[i] = Integer.parseInt(adjHostIdxes[i]); } public void connect() { try { _nextSock = new Socket(getNextHostName(), _defaultPort); } catch(IOException e) { System.err.println(e); } } // accept after connection was estabilished to previous host. public void acceptConnection() { try { _nextSock = _serverSock.accept(); } catch(IOException e) { System.err.println(e); } } public String getNextHostName() { return _nextHostName; } public String getHostName() { return _localHostName; } public int getHostIndex() { return _hostIndex; } public void run() { try { ObjectInputStream in = new ObjectInputStream(_nextSock.getInputStream()); while( !_bEndCondition ) { Object obj = in.readObject(); parseMessage((Message)obj); } } catch(IOException e) { System.err.println(e); } catch(ClassNotFoundException e) { System.err.println(e); } } public void parseMessage(Message msg) { // if the roach visited all cells.. if( msg.checkEndCondition(getHostIndex()) ) { processFinishing(msg); } else if( msg.killMessage) { // if the cell received kill message killClients(msg); } else { // when the roach is on walking~~~ if( msg.targetHostNum == getHostIndex() ) { transmitRoach(msg); } relay(msg); } } public void relay(Message msg) { try { ObjectOutputStream out = new ObjectOutputStream(_nextSock.getOutputStream()); out.writeObject(msg); } catch(IOException e) { System.err.println(e); } } public void showEndStatus() { System.out.println("Random walk finished."); System.out.println("There are" + _numOfVisited + " arrivals"); } public void processFinishing(Message msg) { // if here is the starting point, then send kill signal to others. if( getHostIndex()==0 ) { msg.killMessage = true; relay(msg); } else { // else, relay to the first point. relay(msg); } } public void killClients(Message msg) { // if this is not the last point relay to the last point if( _nextHostIndex<getHostIndex() ) { relay(msg); } else { showEndStatus(); } } public void transmitRoach(Message msg) { if( _numOfVisited==0 ) { msg.numOfRemainCell--; } int nextIdx = new Random().nextInt() % _adjacentCellIdx.length; msg.sourceHostNum = getHostIndex(); msg.targetHostNum = nextIdx; relay(msg); } }
- Message.java
 ~cpp /** * Created by IntelliJ IDEA. * Author: Intaek Lim * Date: 2003. 6. 7. * Time: 오후 10:58:58 */ public class Message { public int targetHostNum; public int sourceHostNum; public int numOfRemainCell; public boolean killMessage; public boolean checkEndCondition(int cellIdx) { return (numOfRemainCell==0); } }
- RandomWalk.java
 ~cpp /** * Created by IntelliJ IDEA. * Author: Intaek Lim * Date: 2003. 6. 8. * Time: 오후 4:7:20 */ public class RandomWalk { public static void main(String args[]) { // localhostname, localHostNum, nextHostName, nextHostNum // sizeX, sizeY, cellInfo String localHostName =args[0]; int localNum = Integer.parseInt(args[1]); String nextHostName = args[2]; int nextHostNum = Integer.parseInt(args[3]); int xSize = Integer.parseInt(args[4]); int ySize = Integer.parseInt(args[5]); String adjInfo = ""; for(int i=6; i<args.length; i++) { adjInfo += args[i] + " "; } System.out.println(adjInfo); } }











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