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<cstdio>
#include<iostream>

using namespace std ;

int mx[] = { 1 ,0 ,0 ,-1 } ;
int my[] = { 0 ,1 ,-1 ,0 } ;

int w ,h ;
int gx ,gy ;

int ok_or_ng( int x ,int y ,bool came[][ 101 ] )
{
	came[ y ][ x ] = false ;

	if( x == gx && y == gy )
		return 1 ;

	for( int i = 0 ; i < 4 ; i++ )
	{
		int xx = x + mx[ i ] ;
		int yy = y + my[ i ] ;
		if( xx > 0 && xx <= w && yy > 0 && yy <= h && came[ yy ][ xx ] )
			return ok_or_ng( xx ,yy ,came ) ;
	}
	return 0 ;
}

void wide( int x ,int y ,int c ,int map[][ 101 ] )
{

	for( int i = 0 ; i < 2 ; i++ )
	{
		for( int j = 0 ; j < 4 ; j++ )
			map[ y + i ][ x + j ] = c ;
	}

	return ;
}

void high( int x ,int y ,int c ,int map[][ 101 ] )
{

	for( int i = 0 ; i < 4 ; i++ )
	{
		for( int j = 0 ; j < 2 ; j++ )
			map[ y + i ][ x + j ] = c ;
	}

	return ;
}

int main()
{
	while( cin >> w >> h ,w & h )
	{
		bool came[ 101 ][ 101 ] = { false } ;
		int map[ 101 ][ 101 ] = { 0 } ;

		int sx ,sy ;

		cin >> sx >> sy ;
		cin >> gx >> gy ;

		int n ;
		cin >> n ;					// 0 w	1 h

		int c ,d ,x, y ;
		for( int i = 0 ; i < n ; i++ )
		{
			cin >> c >> d >> x >> y ;
			d ? high( x ,y ,c ,map ) : wide( x ,y ,c ,map ) ;
		}

		c = map[ gy ][ gx ] ;

		for( int i = 1 ; i <= h ; i++ )
		{
			for( int j = 1 ; j <= w ; j++ )
			{printf( "%d",map[ i ][ j ] ) ;
				if( map[ i ][ j ] == c )
					came[ i ][ j ] = true ;
			}printf( "\n" ) ;
		}

		ok_or_ng( sx ,sy ,came ) ? printf( "OK\n" ) : printf( "NG\n" ) ;
	}

	return 0 ;
}

C++: #include<cstdio>
#include<cstring>
#include<stack>
struct p{
	int x;
	int y;
};
using namespace std;
int main(){
	int w,h,sx,sy,gx,gy,n,c,d,x,y,i,j,k,o;
	int map[100][100];
	int used[100][100];
	int mx[4]={-1,0,1,0};
	int my[4]={0,-1,0,1};
	p v,u;
	stack<p> s;
	while(1){
		scanf("%d %d",&w,&h);
		if(w==0&&h==0){
			break;
		}
		memset(map,0,sizeof(map));
		memset(used,0,sizeof(used));
		scanf("%d %d",&sx,&sy);
		sx--;
		sy--;
		scanf("%d %d",&gx,&gy);
		gx--;
		gy--;
		scanf("%d",&n);
		for(i=0;i<n;i++){
			scanf("%d %d %d %d",&c,&d,&x,&y);
			x--;
			y--;
			if(!d){
				for(j=y;j<y+2;j++){
					for(k=x;k<x+4;k++){
						map[j][k]=c;
					}
				}
			}
			else{
				for(j=y;j<y+4;j++){
					for(k=x;k<x+2;k++){
						map[j][k]=c;
					}
				}
			}
		}
		if(map[sy][sx]!=map[gy][gx]){
			printf("NG\n");
			continue;
		}
		v.x=sx;
		v.y=sy;
		s.push(v);
		o=0;
		while(!s.empty()){
			v=s.top();
			s.pop();
			if(used[v.y][v.x]){
				continue;
			}
			else{
				used[v.y][v.x]=1;
			}
			if(v.x==gx&&v.y==gy){
				o=1;
				break;
			}
			for(i=0;i<4;i++){
				u=v;
				u.x+=mx[i];
				u.y+=my[i];
				if(u.x>=0&&u.x<w&&u.y>=0&&u.y<h&&map[u.y][u.x]==map[sy][sx]){
					s.push(u);
				}
			}
		}
		if(o){
			printf("OK\n");
		}
		else{
			printf("NG\n");
		}
	}
	return 0;
}

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

typedef pair<int,int> P;

#define REP(i,b,n) for(int i=b;i<n;i++)
#define rep(i,n) REP(i,0,n)

const int dy[4] = {-1, 1, 0, 0};
const int dx[4] = {0, 0, -1, 1};
const int MAX_W = 102, MAX_H = 102;
int maze[MAX_H][MAX_W];
int w, h, xs, ys, xg, yg, color;

void solve() {
  memset(maze, 0, sizeof maze);
  int n;
  cin>>xs>>ys>>xg>>yg>>n;
  rep(i,n) {
    int c, d, x, y;
    cin>>c>>d>>x>>y;
    //cout<<c<<d<<x<<y<<endl;
    if (d == 0) {
      REP(j,x,x+4) REP(k,y,y+2) maze[k][j] = c;
    } else {
      REP(j,x,x+2) REP(k,y,y+4) maze[k][j] = c;
    }
  }
  
  /*
  rep(i,h+1) {
    rep(j,w+1) cout<<maze[i][j];
    cout<<endl;
  }*/
  
  if (maze[ys][xs] == 0) {
    cout<<"NG"<<endl;
    return;
  } else {
    color = maze[ys][xs];
  }
  
  bool flag = false;
  queue<P> que;
  que.push(P(xs, ys));
  while (!que.empty() && !flag) {
    P p = que.front(); que.pop();
    int tx = p.first, ty = p.second;
    if (tx == xg && ty == yg) {
      flag = true; continue;
    }
    if (maze[ty][tx] == 0) continue;
    maze[ty][tx] = 0;
    
    rep(z,4) {
      int ttx = tx + dx[z], tty = ty + dy[z];
      if (ttx < 1 || tty < 1 || ttx > w || tty > h) continue;
      if (maze[tty][ttx] != color) continue;
      que.push(P(ttx, tty));
    }
  }
  
  if (flag) {
    cout<<"OK"<<endl;
  } else {
    cout<<"NG"<<endl;
  }
}

int main (int argc, char const* argv[]) {
  while (cin>>w>>h, w||h) {
    solve();
  }
  return 0;
}

C++: #include<iostream>
#include<cstring>
#include<queue>
#include<map>
using namespace std;
int C,goal,n,x,y,xs,ys,xg,yg,mas[110][110]={{0}};
int dx[4]={0,0,1,1};
int dy[4]={0,1,0,1};
int d[110][110];
typedef pair<int,int>P;

int bfs();
int main(){

  while(1){
    goal=0;
    memset(mas,0,sizeof(mas));
    memset(d,0,sizeof(d));
    C = goal = n = x = y = xs = ys = xg = yg = 0;
    cin >> x >> y;//ボードの大きさ。 ※：x=横。y=縦。
    if(x==0 && y==0){
      break;
    }
    cin >> xs >> ys;//スタート地点。
    cin >> xg >> yg;//ゴール地点。
    cin >> n;//ブロックの数。
    
    //色染め。
    int color,dire,xx,yy;
    for(int t=0;t<n;t++){
      cin >> color >> dire >> xx >> yy;

      //横長。
      if(dire==0){
	for(int i=0;i<2;i++){
	  for(int j=0;j<4;j++){
	    mas[yy+i][xx+j]=color;
	  }
	}
      }
      
      //縦長。
      else{
	for(int i=0;i<4;i++){
	  for(int j=0;j<2;j++){
	    mas[yy+i][xx+j]=color;
	  }
	}
      }
      
    }
    
    //通る色　摘出。
    C=mas[ys][xs];
    //cout << "color:" << C << endl;
    
    bfs();
    
    
    if(goal==1){
      cout << "OK" << endl;
    }
    else{
      cout << "NG" << endl;
    }
  }
}

int bfs(){
  queue<P>que;
  memset(d,-1,sizeof(d));
  que.push(P(ys,xs));
  d[ys][xs]=0;
  while(!que.empty()){
    P p=que.front();
    que.pop();
    if(p.first==yg && p.second==xg){
      goal=1;
      break;
    }
    for(int i=0;i<4;i++){
      int ny=p.first+dy[i];
      int nx=p.second+dx[i];
      if(ny>=1 && ny<=y && nx>=1 && nx<=x && mas[ny][nx]==C && d[ny][nx]==-1){
	d[ny][nx] = 1;
	que.push(P(ny,nx));
      }
    }
  }
  return (0);
}