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<stack>
#include<string.h>
using namespace std;
struct ST {
	int a;
	int b;
	int c;
};
long long brock[1000][1000];
long long ds[1000][1000];
int q[4]={0,-1,0,1};
int p[4]={1,0,-1,0};
int main(){
	stack <ST> S;
	ST ma;
	ST ba;
	int w,h;//???????????§??????
	int xs,ys;//??????????????§?¨?
	int xg,yg;//??´????????§?¨?
	int n;//????????????????????°
	int c,d,x,y;//????????????????????±
	int i,j,m,check=0;
	while(1){
		memset(ds,0,sizeof(ds));
		memset(brock,0,sizeof(brock));
		cin>>w>>h;//???????????§????????\???
		if(w==0&&h==0){
			break;
		}
		cin>>xs>>ys>>xg>>yg;//??????????????¨??´???????????§?¨???\???
		cin>>n;//????????????????????°
		for(i=0;i<n;i++){
			cin>>c>>d>>x>>y;
			if(d==0){
				for(m=y;m<y+2;m++){
					for(j=x;j<x+4;j++){
						brock[m][j]=c;
					}
				}
			}
			else{
				for(m=y;m<y+4;m++){
					for(j=x;j<x+2;j++){
						brock[m][j]=c;
					}
				}
			}
		}
		for(i=1;i<w;i++){
			for(j=1;j<h;j++){
				cout<<brock[i][j];
			}
			cout<<endl;
		}
		if(brock[xs][ys]!=brock[xg][yg]){
			cout<<"NG"<<endl;
		}
		else{
			ma.a=xs;
			ma.b=ys;
			ma.c=brock[xs][ys];
			ds[xs][ys]=1;
			S.push(ma);
			check=0;
			while(!S.empty()){
				ba=S.top();
				S.pop();
				ds[ba.a][ba.b]=1;
				if(ba.a==xg&&ba.b==yg){
					check=1;
					break;
				}
				if(ba.c==brock[xg][yg]){
					for(i=0;i<4;i++){
						if(ba.a+p[i]>0&&ba.a+p[i]<=w&&ba.b+q[i]>0&&ba.b+q[i]<=h&&ds[ba.a+p[i]][ba.b+q[i]]==0){
							ma.a=ba.a+p[i];
							ma.b=ba.b+q[i];
							ma.c=brock[ba.a+p[i]][ba.b+q[i]];
							S.push(ma);
						}
					}
				}
			}
			if(check==1){
				cout<<"OK"<<endl;
			}
			else{
				cout<<"NG"<<endl;
			}
		}
	}
	return 0;
}

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[][ 100 ] )
{
	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[][ 100 ] )
{

	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[][ 100 ] )
{

	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[ 100 ][ 100 ] = { false } ;
		int map[ 100 ][ 100 ] = { 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 ;
			}
		}

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

	return 0 ;
}

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, w,h;

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

    blocks[y][x] = 9;
    
    dfs(target, x + 1, y);
    dfs(target, x - 1, y);
    dfs(target, x, y + 1);
    dfs(target, x, y - 1);
    return;
}

int main(){
    int xs, ys, n;
    while(cin >> w >> h, w||h){
        rep(i,h) rep(j,w) blocks[i][j] = 0;
        cin >> xs >> ys >> xg >> yg >> n;
        xs--; ys--; xg--; yg--;
        rep(i,n){
            int c, d, x, y;
            cin >> c >> d >> x >> y;
            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;
    }
}