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++: //
//  main.cpp
//  joi
//
//  Created by 8595198919 on 14/06/09.
//  Copyright (c) 2014年 8595198919. All rights reserved.
//

#include <iostream>
#include <list>
#include <stack>
#define rep(i,n) for(int i = 0;i < n;i++)
#define Rep(i,n) for(int i = 1;i <= n;i++)
#define fs first
#define sc second
#define mp make_pair
using namespace std;

int w,h;
int xs,ys,xg,yg;
int n;
int goal[2];
int dx[4]={1,0,0,-1};
int dy[4]={0,1,-1,0};
int map_[105][105];
bool went[105][105];
int c,d,x,y;

bool search(int x,int y){
    if(map_[x][y]==0)
        return 0;
    if(x==xg&&y==yg)
        return 1;
    rep(i,4){
        int xnext = x +dx[i];
        int ynext = y +dy[i];
        if(went[xnext][ynext])
            continue;
        if(map_[xnext][ynext]==map_[x][y]){
            went[x][y]=true;
            if(search(xnext,ynext))
                return 1;
        }
    }
    return 0;
}


int main(){
    while(scanf("%d %d",&w,&h),(w!=0&&h!=0)){
        rep(i,w+5){
            rep(j,h+5){
                map_[i][j]=0;
                went[i][j]=0;
            }
        }
        scanf("%d %d %d %d %d",&xs,&ys,&xg,&yg,&n);
        xs++,ys++,xg++,yg++;
        rep(i,n){
            scanf("%d %d %d %d",&c,&d,&x,&y);
            x++,y++;
            rep(i,(dx[d]+1)*2){
                rep(j,(dy[d]+1)*2){
                    map_[x+i][y+j] = c;
                }
            }
        }
        if(search(xs,ys))
            cout << "OK" << endl;
        else
            cout <<"NG"<<endl;
    }
}

C++: #include <iostream>
#include <algorithm>
#include <cassert>
#include <cctype>
#include <complex>
#include <cstdio>
#include <map>
#include <math.h>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>
using namespace std;

int show=0;
int w,h,sx,sy,gx,gy,d[101][101],dx[4]={1,0,-1,0},dy[4]={0,1,0,-1},C;
int field[101][101];
const int INF=9999999;
typedef pair<int,int> P;

void bfs(){
	queue<P> que;
	for(int i=1;i<=h;i++)for(int j=1;j<=w;j++)d[i][j]=INF;
	que.push(P(sy,sx));
	d[sy][sx]=0;
	while(!que.empty()){
		P p=que.front(); que.pop();
		if(p.first==gy&&p.second==gx)break;
		for(int i=0;i<4;i++){
			int ny=p.first+dy[i],nx=p.second+dx[i];
			if(1<=ny&&ny<=h&&1<=nx&&nx<=w&&field[ny][nx]==C&&d[ny][nx]==INF){
			que.push(P(ny,nx));
			d[ny][nx]=d[p.first][p.second]+1;
			}
		}
	}
	if(d[gy][gx]==INF)cout<<"NG"<<endl;
	else cout<<"OK"<<endl;
}

int main() {
	while(cin>>w>>h){
		if(!h)return 0;
		int n,c,di,x,y;
		cin>>sx>>sy>>gx>>gy>>n;
		for(int i=1;i<=h;i++)for(int j=1;j<=w;j++)field[i][j]=0;
		for(int i=0;i<n;i++){
			cin>>c>>di>>x>>y;
			for(int j=y;j<y+2+di*2;j++)for(int k=x;k<x+2+!di*2;k++)field[j][k]=c;
		}
		C=field[1][1];
		if(!C)cout<<"NG"<<endl;
		else bfs();
		if(show){
			for(int i=1;i<=h;i++){for(int j=1;j<=w;j++){if(field[i][j])cout<<field[i][j];else cout<<" ";}cout<<endl;}
			for(int i=1;i<=h;i++){for(int j=1;j<=w;j++){if(d[i][j]<INF)cout<<d[i][j]<<" ";else cout<<"  ";}cout<<endl;}
		}
	}
}

C++: #include <bits/stdc++.h>
 
using namespace std;
 
#define MAX 101
 
int H, W, sx, sy, gx, gy;
int color, dir, field[MAX][MAX];
 
struct P {
    int x, y;
    P(int x, int y) : x(x), y(y) {}
};
 
const int dx[] = {-1, 0, 0, 1};
const int dy[] = {0, -1, 1, 0};
 
bool check(int y, int x)
{
    if (0 <= y && y < H && 0 <= x && x < W) {
	return true;
    }
    return false;
}
 
void paint(int y, int x)
{
    if (!dir) {
	for (int i = 0; i < 2; i++) {
	    for (int j = 0; j < 4; j++) {
		field[y+i][x+j] = color;
	    }
	}
    } else {
	for (int i = 0; i < 4; i++) {
	    for (int j = 0; j < 2; j++) {
		field[y+i][x+j] = color;
	    }
	}
    }
}
 
bool bfs()
{
    bool used[MAX][MAX];
    memset(used, false, sizeof(used));
    used[sy][sx] = true;
 
    queue<P> Q;
    Q.push(P(sx, sy));
 
    while (!Q.empty()) {
	P p = Q.front(); Q.pop();
 
	if (field[p.y][p.x] == -1) continue;
 
	for (int i = 0; i < 4; i++) {
	    int nx = p.x + dx[i];
	    int ny = p.y + dy[i];
 
	    if (!check(ny, nx) || used[ny][nx] || 
	       field[p.y][p.x] != field[ny][nx]) continue;
 
	    used[ny][nx] = true;
	    Q.push(P(nx, ny));     
	}
    }
    return used[gy][gx];
}
 
int main()
{
    int n, x, y;
    while (cin >> W >> H, (W | H)) {
	memset(field, -1, sizeof(field));
 
	cin >> sx >> sy >> gx >> gy >> n;
	sy--, sx--, gy--, gx--;
 
	for (int i = 0; i < n; i++) {
	    cin >> color >> dir >> x >> y;
	    y--, x--;
	    paint(y, x);
	}
	cout << (bfs() ? "OK" : "NG") << endl;
    }
    return 0;
}

C++: #include<iostream>

using namespace std;

int dx[4]={1,0,-1,0};
int dy[4]={0,1,0,-1};
int N;
int W,H;
pair<int,int>s;
pair<int,int>g;
int sc;
int map[103][103]={0};
bool flag[103][103]={0};
int ans=0;

bool se(int x,int y){
	if(x==g.first && y==g.second)ans=1;
	for(int i=0;i<4;i++){
		int xx=x+dx[i];
		int yy=dy[i]+y;
		if(xx>=0 &&yy>=0 &&xx<W &&yy<H && sc==map[xx][yy]&& flag==0){
			flag[xx][yy]=1;
			se(xx,yy);
		}
	}
	return 0;
}


int main(){
	
	while(cin>>W>>H>>s.first>>s.second>>g.first>>g.second>>N && W && H){
		int d,c,x,y;
		
		for(int i=0;i<N;i++){
			cin>>c>>d>>x>>y;
			if(d){
				for(int i=x;i<x+2;i++){
					for(int j=y;j<y+4;j++){
						map[i][j]=c;
				}
			}
		}else{
			for(int i=x;i<x+4;i++){
				for(int j=y;j<y+2;j++){
					map[i][j]=c;
				}
			}
		}
		}
		sc=map[s.first][s.second];
		flag[s.first][s.second]=1;
		if(se(s.first,s.second))cout<<"OK"<<endl;
		else cout<<"NG"<<endl;

	}
	return 0;
}