Go: package main

import (
	"bufio"
	"os"
	"strings"
	"strconv"
	"fmt"
)

var scanner = bufio.NewScanner(os.Stdin)

var (
	dx = []int{0, -1, 0, 1}
	dy = []int{1, 0, -1, 0}
)

func main() {
	for scanner.Scan() {
		buf := strings.Split(scanner.Text(), " ")
		w, _ := strconv.Atoi(buf[0])
		h, _ := strconv.Atoi(buf[1])
		if w == 0 && h == 0 {
			break
		}
		scanner.Scan()
		buf_ := strings.Split(scanner.Text(), " ")
		xs, _ := strconv.Atoi(buf_[0])
		ys, _ := strconv.Atoi(buf_[1])
		scanner.Scan()
		buf__ := strings.Split(scanner.Text(), " ")
		xg, _ := strconv.Atoi(buf__[0])
		yg, _ := strconv.Atoi(buf__[1])
		xs--
		ys--
		xg--
		yg--
		scanner.Scan()
		n, _ := strconv.Atoi(scanner.Text())
		field := make([][]int, 100)
		for i := range  field {
			field[i] = make([]int, 100)
		}
		visited := make([][]bool, 100)
		for i := range visited {
			visited[i] = make([]bool, 100)
		}
		for i := 0; i < n; i++ {
			scanner.Scan()
			buf___ := strings.Split(scanner.Text(), " ")
			c, _ := strconv.Atoi(buf___[0])
			d, _ := strconv.Atoi(buf___[1])
			x, _ := strconv.Atoi(buf___[2])
			y, _ := strconv.Atoi(buf___[3])
			x--
			y--
			switch d {
			case 0:
				for j := 0; j < 4; j++ {
					for k := 0; k < 2; k++ {
						field[x+j][y+k] = c
					}
				}
			case 1:
				for j := 0; j < 2; j++ {
					for k := 0; k < 4; k++ {
						field[x+j][y+k] = c
					}
				}
			}
		}
		if field[xs][ys] != field[xg][yg] || // スタートとゴールの色が等しくないと"NG"
			field[xs][ys] == 0 { // スタートの色が無職
			fmt.Println("NG")
			continue
		}
		Q := make([]Entry, 0)
		visited[xs][ys] = true
		Q = append(Q, Entry{xs, ys})
		for len(Q) > 0 {
			row := Q[0].x
			col := Q[0].y
			Q = Q[1:]
			for i := 0; i < 4; i++ {
				if 0 <= row+dx[i] && row+dx[i] < w &&
					0 <= col+dy[i] && col+dy[i] < h && // 移動可能な範囲内かどうか
					!visited[row + dx[i]][col + dy[i]] && // 訪問済みか
					field[row+dx[i]][col+dy[i]]==field[row][col] { // 色が同じかどうか
						visited[row+dx[i]][col+dy[i]] = true
						Q = append(Q, Entry{row+dx[i],col+dy[i]})
				}
			}
		}
		if visited[xg][yg] {
			fmt.Println("OK")
		} else {
			fmt.Println("NG")
		}
	}
}

type Entry struct {
	x, y int
}

C++: #include <iostream>
#include <queue>
using namespace std;


#define rep(i,n) for(short i = 0; i < n; i++)
#define MAX 50

int dx[] = {0,0,-1,1},
	dy[] = {1,-1,0,0};

typedef pair<short,short> P;
P S,G;
short w,h;
short maze[MAX][MAX];
short color;

bool check()
{
	queue<P> que;
	que.push(S);
	color = maze[S.second][S.first];

	short nx,ny;
	while(que.size()){
		P p = que.front();	que.pop();

		if(p == G){
			while(que.size())
				que.pop();
			return true;
		}

		rep(i,4){
			nx = p.first + dx[i], ny = p.second + dy[i];
			
			if(nx > -1 && ny > -1 && nx < w && ny < h &&
				maze[ny][nx] == color){
					maze[ny][nx] = -1;
					que.push(P(nx,ny));
			}

		}
	}


	
	return false;
}

int main(void)
{
	short n,c,d,x,y;

	while(cin >> w >> h, w){
		cin >> S.first >> S.second;
		cin >> G.first >> G.second;
		S.first = S.first / 2;
		S.second= S.second/ 2;

		cin >> n;

		rep(i,n){
			cin >> c >> d >> x >> y;
			x /= 2;
			y /= 2;
			x++;
			y++;

			if(d == 0)
				maze[y][x] = maze[y][x+1] = c;
			else
				maze[y][x] = maze[y+1][x] = c;
		}
		
		if(check())
			cout << "OK\n";
		else
			cout << "NG\n";
/*
		rep(i,y){
			rep(j,x)
				printf("%2d", maze[i][j]);
			cout << endl;
		}

*/
	}
	
	return 0;
}

C++: #include<iostream>
#include<algorithm>
#include<string>
	using namespace std;
	int xs,ys,w,h,n,ban[111][111],xg,yg;bool visited[101][101];
	bool dfs(int x,int y,int c){
		//cout<<x<<" "<<y<<endl;
				if(c-1||ban[x][y]!=c)return false;
		if(xg==x&&yg==y)return true;
		//if(ban[xs][ys]==0)return false;
		if(ban[x+1][y]==c&&visited[x+1][y]==false){
			visited[x+1][y]=true;
			if(dfs(x+1,y,c))return true;
		}
		if(ban[x][y+1]==c&&visited[x][y+1]==false){
			visited[x][y+1]=true;
			if(dfs(x,y+1,c))return true;
		}
		if(x>=2&&ban[x-1][y]==c&&visited[x-1][y]==false){
			visited[x-1][y]=true;
			if(dfs(x-1,y,c))return true;
		}
		if(y>=2&&ban[x][y-1]==c&&visited[x][y-1]==false){
			visited[x][y-1]=true;
			if(dfs(x,y-1,c))return true;
		}
		return false;
	}


int main(){

	while(cin>>w>>h&&w&&h){
	cin>>xs>>ys>>xg>>yg>>n;
	for(int i=0;i<101;i++)
	for(int j=0;j<101;j++)ban[i][j]=-1,visited[i][j]=false;
	
	for(int i=0;i<n;i++){
		int c,d,x,y;
		cin>>c>>d>>x>>y;
		if(!d){
			for(int i=x;i<x+4;i++){
				for(int j=y;j<y+2;j++){
					ban[i][j]=c;
				}
			}
		}
		else{
		for(int i=x;i<x+2;i++){
				for(int j=y;j<y+4;j++){
					ban[i][j]=c;
				}
			}
		}
		}
		if(dfs(xs,ys,ban[xs][ys]))cout<<"OK"<<endl;
	else cout<<"NG"<<endl;
	}
	return 0;
	}

C++: #include<iostream>
using namespace std;

int F[102][102];

void
DFS (int Y, int X, int A)
{
  if (F[Y][X] != A)
    return;

  F[Y][X] = 7;

  DFS (Y - 1, X, A);
  DFS (Y, X + 1, A);
  DFS (Y + 1, X, A);
  DFS (Y, X - 1, A);
}

int
main ()
{
  int w, h;
  int xs, ys;
  int xg, yg;
  int n;
  int c, d, x, y;

  while (true)
    {
      cin >> w >> h;
      if (w == 0 && h == 0)
	break;
      cin >> xs >> ys;
      cin >> xg >> yg;
      cin >> n;

      for (int i = 0; i < n; i++)
	{
	  cin >> c >> d >> x >> y;
	  if (d == 0)
	    {
	      for (int a = 0; a < 4; a++)
		{
		  for (int b = 0; b < 2; b++)
		    {
		      F[y + b][x + a] = c;
		    }
		}

	    }
	  else
	    {
	      for (int a = 0; a < 2; a++)
		{
		  for (int b = 0; b < 4; b++)
		    {
		      F[y + b][x + a] = c;
		    }
		}
	    }

	}


      if (F[ys][xs] == 1 || F[ys][xs] == 2 || F[ys][xs] == 3
	  || F[ys][xs] == 4 || F[ys][xs] == 5)
	{
	  DFS (ys, xs, F[ys][xs]);
	}

      if (F[yg][xg] == F[ys][xs])
	{
	  cout << "OK" << endl;
	}
      else
	{
	  cout << "NG" << endl;
	}
   
    /*for (int y = 0; y < h; y++)
	{
	  for (int x = 0; x < w; x++)
	    {
	      cout << F[y][x];
	    }
         cout << endl;
	}*/
   
    for (int y = 1; y <= h; y++)
	{
	  for (int x = 1; x <= w; x++)
	    {
	      F[y][x] = 0;
	    }
	}

    
   
    }

  return 0;
}

C++: #include <iostream>
using namespace std;
int board[100][100],w,h,xg,yg;
bool f(int y,int x){
	board[y][x] = 0;
	int dy[] = {-1,0,0,1},dx[] = {0,-1,1,0},i;
	if(y == yg - 1 && x == xg -1) return true;
	for(i = 0;i < 4;i++){
		if(y + dy[i] > -1 && y + dy[i] < h && x + dx[i] > -1 && x + dx[i] < w){
			if(board[y+dy[i]][x+dx[i]] == 2){
				if(f(y+dy[i],x+dx[i])) return true;
			}
		}
	}
	return false;
}
int main(){
	int xs,ys,n,i,c,d,x,y,j,k;
	while(cin >> w >> h && (w != 0 && h != 0)){
		cin >> xs >> ys;
		cin >> xg >> yg;
		cin >> n;
		for(i = 0;i < n;i++){
			cin >> c >> d >> x >> y;
			x -= 1;
			y -= 1;
			if(d == 0){
				for(j = 0;j < 2;j++){
					for(k = 0;k < 4;k++){
						board[y+j][x+k] = c;
					}
				}
			}
			else if(d == 1){
				for(j = 0;j < 2;j++){
					for(k = 0;k < 4;k++){
						board[y+k][x+j] = c;
					}
				}
			}
		}
		if(board[y - 1][x - 1] == 2){
			if(f(ys - 1,xs -1)) cout << "OK" << endl;
			else cout << "NG" << endl;
		}
		else cout << "NG" << endl;
		for(j = 0;j < 100;j++){
			for(i = 0;i < 100;i++){
				board[j][i] = 0;
			}
		}
	}
	return 0;
}