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[][ 110 ] )
{
	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 ] )
		{
			came[ yy ][ xx ] = false ;
			return ok_or_ng( xx ,yy ,came ) ;
		}
	}
	return 0 ;
}

void wide( int x ,int y ,int c ,int map[][ 110 ] )
{

	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[][ 110 ] )
{

	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 )
	{
		if( w == h && w == 0 )
		return 0 ;
		bool came[ 110 ][ 110 ] = { false } ;
		int map[ 110 ][ 110 ] = { 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 ] ;

		came[ sy ][ sx ] = false ;	//

		for( int i = 1 ; i <= h ; i++ )
		{
			for( int j = 1 ; j <= w ; j++ )
			{
				if( map[ i ][ j ] == c )
					came[ i ][ j ] = true ;
			}
		}

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

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

int w, h;
vector < vector <int> > block_map;

int xs, ys;
int xg, yg;

const int dx[4] = { 1, 0, -1, 0 };
const int dy[4] = { 0, -1, 0, 1 };

bool dfs( int x, int y )
{
	if ( block_map[y][x] == 0 || block_map[y][x] != block_map[yg][xg] )
		return false;
	if ( x == xg && y == yg )
		return true;

	block_map[y][x] = -1;
	for ( int i = 0; i < 4; i++ )
	{
		int nx = x + dx[i];
		int ny = y + dy[i];
		if ( nx < 0 || nx >= w || ny < 0 || ny >= h )
			continue;

		if ( block_map[ny][nx] != -1 && block_map[ny][nx] == block_map[yg][xg] )
		{
			if ( dfs( nx, ny ) )
			{
				return true;
			}
		}
	}

	return false;
}

int main( void )
{
	while ( 1 )
	{
		cin >> w >> h;
		if ( w == 0 && h == 0 )
			break;

		block_map = vector < vector <int> >( h, vector <int>(w,0) );
		
		cin >> xs >> ys >> xg >> yg;

		xs--;
		ys--;
		xg--;
		yg--;

		int n;
		cin >> n;
		for ( int i = 0; i < n; i++ )
		{
			int c, d, x, y;
			cin >> c >> d >> x >> y;
			x--;
			y--;

			if ( d == 0 )
			{
				for ( int by = 0; by < 2; by++ )
				{
					for ( int bx = 0; bx < 4; bx++ )
					{
						block_map[y+by][x+bx] = c;
					}
				}
			}
			else
			{
				for ( int by = 0; by < 4; by++ )
				{
					for ( int bx = 0; bx < 2; bx++ )
					{
						block_map[y+by][x+bx] = c;
					}
				}
			}
		}

		if ( dfs( xs, ys ) )
			cout << "OK" << endl;
		else
			cout << "NG" << endl;

	}
	return 0;
}

C++: #include <bits/stdc++.h>

#define rep(i, j) FOR(i, 0, j)
#define rep2(i, k) for(int i = 1; i <= k; ++i)
#define FOR(i, j, k) for(int i = j; i < k; ++i)
#define INF (1 << 30)

using namespace std;
 
const int dx[] = {1, 0, -1, 0}, dy[] = {0, 1, 0, -1};

int field[105][105];
int h, w, sx, sy, gx, gy, n;
int col, dire, x, y;
int scol;

bool dfs(int nx, int ny) {
	field[ny][nx] = 0;
	if(nx == gx && ny == gy) return true;
	rep(i, 4) {
		int tx = nx + dx[i];
		int ty = ny + dy[i];
		if(tx <= w && tx > 0 && ty <= h && field[ty][tx] == scol) dfs(tx, ty);
	}
	return false;
}

int main() {
	while(cin >> w >> h, w || h) {
		memset(field, 0, sizeof(field));
		int scol = 0;
		cin >> sx >> sy >> gx >> gy;
		cin >> n;
		rep(k, n) {
			cin >> col >> dire >> x >> y;
			if(dire) {
				rep(i, 4) rep(j, 2) field[y + i][x + j] = col;
			}
			else {
				rep(i, 2) rep(j, 4) field[y + i][x + j] = col;
			}
			//rep(j, (dire?4:2)) rep(k, (dire?2:4)) field[x + j][y + k] = col;
		}
		scol = field[sx][sy];
		/*rep(i, h + 1){
			rep(j, w + 1) cout << field[i][j] << " ";
			puts("");
  		}*/
		if(dfs(sx, sy) || field[y][x] != 0) cout << "OK" << endl;
		else cout << "NG" << endl; 
	}
	return 0;
}

C++: #include <iostream>
using namespace std;
int F[102][102];

void DFScolor(int X,int Y,int color){

	if(F[X][Y]!=color)
		return;
	
	F[X][Y]=9;
	DFScolor(X-1,Y,color);
	DFScolor(X,Y+1,color);
	DFScolor(X+1,Y,color);
	DFScolor(X,Y-1,color);
	
}


int main(){
while(1){
	int H,W,xg,yg,xs,ys,n,count=0;
	cin>>H;
	if(H==0)
		count++;
	cin>>W;
	if(W==0)
		count++;
	if(count==2)
		return 0;
	cin>>xs>>ys;
	cin>>xg>>yg;	
	cin>>n;
	int c,d,x,y;
	int xb[n],yb[n],colo[n];
	for(int i=0;i<n;i++){
		
		cin>>c>>d>>x>>y;
		colo[i]=c;
		xb[i]=x;
		yb[i]=y;
		if(d==0){
			for(int o=y;o<y+2;o++){
				for(int j=x;j<x+4;j++){
					F[j][o]=c;
				}
			}
		}
		else if(d==1){
			for(int o=y;o<y+4;o++){
				for(int j=x;j<x+2;j++){
					F[j][o]=c;
				}
			}
		}
		
	}
	
	for(int i=0;i<n;i++){
		if(xb[i]==xs&&yb[i]==ys){
			DFScolor(xb[i],yb[i],colo[i]);
			break;
		}
	}
	if(F[xg][yg]==9)
		cout<<"OK"<<endl;
	else
		cout<<"NG"<<endl;
	
}
}