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 ] ,int map[][ 110 ] )
{

	if( x == gx && y == gy )
		return 1 ;
	came[ y ][ x ] = false ;
	map[ y ][ x ] = -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 ,map ) ;
	}
	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 ] ;


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

		if( map[ gy ][ gx ] == map[ sy ][ sx ] )
			ok_or_ng( sx ,sy ,came ,map ) ? printf( "OK\n" ) : printf( "NG\n" ) ;
		else
			printf( "NG\n" ) ;
		/*if( came[ gy ][ gx ] ){
		for( int i = 0 ; i <= h + 1 ; i++ )
		{
			for( int j = 0 ; j <= w + 1 ; j++ )
				cout << map[ i ][ j ] ;
			cout << endl ;
		}}*/
	}
}

C++: #include<stdio.h>
#include<algorithm>
#include<functional>
int w,h;
int xs,ys,xg,yg;
int n;
int c,d,x,y;
int map[101][101];
int flg=0,temp;
void func(int ,int);
using namespace std;
int main(void){
	while(1){
		scanf("%d %d",&w,&h);
		if(w==0 && h==0){
			break;
		}
		int i,j,k;
		for(i=1;i<=100;i++){
			for(j=1;j<=100;j++){
				map[i][j]=0;
			}
		}
		scanf("%d %d %d %d %d",&xs,&ys,&xg,&yg,&n);
		for(i=0;i<n;i++){
			scanf("%d %d %d %d",&c,&d,&x,&y);
			if(d==0){
				for(k=0;k<=1;k++){
					for(j=0;j<=3;j++){
						map[y+k][x+j]=c;
					}
				}
			}
			if(d==1){
				for(k=0;k<=3;k++){
					for(j=0;j<=1;j++){
						map[y+k][x+j]=c;
					}
				}
			}
			/*for(j=1;j<=10;j++){
				for(k=1;k<=10;k++){
					printf("%d ",map[j][k]);
				}
				printf("\n");
			}
			printf("\n");*/
		}
		flg=0;
		if(map[ys][xs]==map[yg][xg] && map[ys][xs]!=0){
			temp=map[ys][xs];
			map[ys][xs]=0;
			func(ys,xs);
		}/*
		for(i=1;i<=10;i++){
			for(j=1;j<=10;j++){
				printf("%d ",map[i][j]);
			}
			printf("\n");
		}*/
		if(flg==1){
			printf("OK\n");
		}
		else {
			printf("NG\n");
		}
	}
	return 0;
}
void func(int yy,int xx){
	int dy[4]={0,1,0,-1},dx[4]={1,0,-1,0};
	int i;
	if(flg==0){
		for(i=0;i<4;i++){
			yy=yy+dy[i];
			xx=xx+dx[i];
			if(yy<=h && yy>=1 && xx<=w && xx>=1 && map[yy][xx]==temp){
				map[yy][xx]=0;
				if(xg==xx && yg==yy){
					flg=1;
					break;
				}
				func(yy,xx);
			}
		}
	}
}

C++: #include<bits/stdc++.h>
#define range(i,a,b) for(int i = (a); i < (b); i++)
#define rep(i,b) range(i,0,b)
#define pb(a) push_back(a)
#define all(a) (a).begin(), (a).end()
#define debug(x) cout << "debug " << x << endl;
using namespace std;

bool isMaze;
int blocks[105][105], xg, yg;

void dfs(int target, int x, int y){
    if(x == xg && y == yg){
        isMaze = true;
        return;
    }
    if(blocks[y][x] != target || blocks[y][x] == 0){
        return;
    }

    blocks[y][x] = 0;
    
    dfs(target, x + 1, y);
    dfs(target, x - 1, y);
    dfs(target, x, y + 1);
    dfs(target, x, y - 1);
}

int main(){
    int w, h, xs, ys, n;
    while(cin >> w >> h, w||h){
        rep(i,105) rep(j,105) blocks[i][j] = 0;
        cin >> xs >> ys >> xg >> yg >> n;
        rep(i,n){
            int c, d, x, y;
            cin >> c >> d >> x >> y;
            if(d == 0){
                rep(j,2) rep(k,4) blocks[y + j][x + k] = c;
            }else{
                rep(j,4) rep(k,2) blocks[y + j][x + k] = c;
            }
        }
        isMaze = false;
        dfs(blocks[ys][xs], xs, ys);

        if(isMaze) cout << "OK" << endl;
        else cout << "NG" << endl;
    }
}

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

using namespace std;

bool dfs(int xs,int ys,int xg,int yg,vector<vector<bool> >& canGo){
canGo[xs][ys]=false;
if(xs==xg&&ys==yg)return true;
if(canGo[xs+1][ys]){if(dfs(xs+1,ys,xg,yg,canGo))return true;}
if(canGo[xs-1][ys]){if(dfs(xs-1,ys,xg,yg,canGo))return true;}
if(canGo[xs][ys+1]){if(dfs(xs,ys+1,xg,yg,canGo))return true;}
if(canGo[xs][ys-1]){if(dfs(xs,ys-1,xg,yg,canGo))return true;}
return false;
}
int main(void){
int w,h,xs,ys,xg,yg,n;
bool ans,endflag;
vector<vector<bool> > blockmap;
while(true){
cin>>w>>h;
if(w==0&&h==0)break;
cin>>xs>>ys>>xg>>yg>>n;
blockmap=vector<vector<bool> >(w+2,vector<bool>(h+2,true));
for(int i=0;i<n;i++){
    int c,d,x,y;
    cin>>c>>d>>x>>y;
    if(c!=2){
        blockmap[x+1][y+1]=false;
        blockmap[x+2][y+1]=false;
        blockmap[x+1][y+2]=false;
        blockmap[x+2][y+2]=false;
        if(d==0){
            blockmap[x+3][y+1]=false;
            blockmap[x+3][y+2]=false;
            blockmap[x+4][y+1]=false;
            blockmap[x+4][y+2]=false;
        }
        else {
            blockmap[x+1][y+2]=false;
            blockmap[x+2][y+3]=false;
            blockmap[x+1][y+4]=false;
            blockmap[x+2][y+4]=false;
        }
    }
}
ans=dfs(xs+1,ys+1,xg+1,yg+1,blockmap);
if(ans)cout<<"OK"<<endl;
else cout<<"NG"<<endl;
}
return 0;
}