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 <string.h>
using namespace std;

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

int field[101][101];

int xs,ys,xg,yg;

void SetBlock(int c,int d,int x,int y)
{
	if(d==0){//横なが
		for(int ay=0;ay<2;++ay){
			for(int ax=0;ax<4;++ax){
				field[y+ay][x+ax] = c;
			}
		}
	}
	if(d==1){//縦なが
		for(int ay=0;ay<4;++ay){
			for(int ax=0;ax<2;++ax){
				field[y+ay][x+ax] = c;
			}
		}
	}
}

bool dfs(int x,int y)
{
	int c = field[y][x];
	field[y][x] = 0;
	if(x == xg && y == yg) return true;
	for(int i=0;i<4;++i){
		if(c==field[y+dy[i]][x+dx[i]])if(dfs(x+dx[i],y+dy[i]))return true;
	}
	return false;
}

int main(void)
{
	while(1){
		int w,h;
		int n;
		memset(field,0,sizeof(field));
		cin >> w >> h;
		if(w==0&&h==0)
			return 0;
		cin >> xs >> ys;
		cin >> xg >> yg;
		cin >> n;
		for(int i=0;i<n;++i){
			int c,d,x,y;
			cin >> c >> d >> x >> y;
			SetBlock(c,d,x,y);
		}
		if(field[ys][xs] == 0)
			cout << "NG" << endl;
		else
		{
			if(dfs(xs,ys))
				cout << "OK" << endl;
			else
				cout << "NG" << endl;
		}
	}
	return 0;
}

C++: #include<iostream>
using namespace std;
#define MAX 105

int map[MAX][MAX];
int xs, ys, xg, yg;
int n;
int w, h;
int c, d, x, y;
int count = 0;
int color;
int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};

void jadge(int x, int y){
	if(count == 0){
		if(0 <= x && x <= w && 0 <= y && y <= h && map[x][y] == color){
			map[x][y] = 9;
			if(x == xg && y == yg){
				count = 1;
				return;
			}
			for(int i=0; i < 4; i++){
				jadge(x+dx[i], y+dy[i]);
			}
		}
	}
}
int main(){
	while(1){
		count = 0;

		for(int i=0; i < MAX; i++){
			for(int j=0; j< MAX; j++){
				map[i][j] = 0;
			}
		}

		cin >> h >> w;
		if(w == 0 && h == 0) break;

		cin >> ys >> xs;
		cin >> yg >> xg;
		xs--; ys--; xg--; yg--;
		cin >> n;
		for(int i=0; i < n; i++){
			cin >> c >> d >> y >> x;

			for(int i=0;  i < 4; i++){
				for(int j=0; j < 2; j++){
					if(d == 1){
						map[x-1+i][y-1+j] = c;
					}
					else{
						map[x-1+j][y-1+i] = c;
					}
				}
			}
		}
		/*
		for(int i=0; i < w; i++){
			for(int j=0; j < h; j++){
				cout << map[i][j];
			}
			cout << endl;
		}
		*/
		if(map[xs][ys] != map[xg][yg]){
			cout << "NG" << endl;
			continue;
		}
		else if(map[xs][ys] == 0 || map[xg][yg] == 0){
			cout << "NG" << endl;
			continue;
		}
		color = map[xs][ys];

		jadge(xs, ys);

		if(count == 1) cout << "OK" << endl;
		else cout << "NG" << endl;
	}
	return 0;
}

C++: #include<iostream>
#include<string>
#include<algorithm>
#include<list>
#include<set>
#include<map>
#include<queue>
#include<stack>
#include<numeric>
#include<vector>
#include<cstdio>
#include<climits>
#include<cfloat>
#include<cstring>
#define foreach(t,p,it) for(t::iterator it=p.begin(),it!=p.end(),++it)
#define all(p) p.begin(),p.end()
#define rep(i,n) for(int i=0;i<n;i++)
#define REP(n) rep(i,n)
using namespace std;

const int W=210,H = 210;
int block[W][H];
int ans;

int w,h,xs,ys,xg,yg,n,c,d,x,y;
void solve(int xi,int yi)
{
    if(xi==xg && yi==yg){ ans = 1; return;}
    if(block[xi][yi] == 0) return;

    if(block[xi][yi] == c)
    {
        block[xi][yi] = 0;
        solve(xi-1, yi);
        solve(xi, yi-1);
        solve(xi+1, yi);
        solve(xi, yi+1);
    }
    block[xi][yi] = 0;
    return;
}

int main()
{
    while(cin >> w >> h )
    {
        if(w==0 && h==0) break;
        memset(block,0,sizeof(block));
        ans = 0;
        cin >> xs >> ys;
        cin >> xg >> yg;
        cin >> n;
        REP(n)
        {
            cin >> c >> d >> x >> y;
            if(d == 1) //tate
            {
                block[x][y] = c;
                block[x][y+1] =c;
                block[x][y+2] = c;
                block[x][y+3] = c;
                block[x+1][y] = c;
                block[x+1][y+1] = c;
                block[x+1][y+2] = c;
                block[x+1][y+3] = c;
            }
            else
            {
                block[x][y] = c;
                block[x+1][y] = c;
                block[x+2][y] = c;
                block[x+3][y] = c;
                block[x][y+1] = c;
                block[x+1][y+1] = c;
                block[x+2][y+1] = c;
                block[x+3][y+1] = c;
            }
        }
        c = block[xs][ys];
        solve(xs,ys);

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

    return 0;
}

C++: #include<iostream>
using namespace std;
int w,h,xs,ys,xg,yg,n;
int map[101][101];
string ans;
char start;
void fun(int y,int x){
    if(map[y][x]==start){
        map[y][x]=7;
    }
    else
        return;
    if(x<1||w<x||y<1||h<y)
        return;
    if(map[y][x]==map[yg][xg]){
        ans="OK";
        return;
    }
    fun(y,x+1);
    fun(y,x-1);
    fun(y+1,x);
    fun(y-1,x);
}
void mc(){
    int c,d,x,y;
    for(int i=0;i<n;i++){
        cin >> c >> d >> x >> y;
        if(d==0){
            for(int j=0;j<2;j++){
                for(int k=0;k<4;k++){
                    map[y+j][x+k]=c;
                }
            }
        }
        else{
            for(int j=0;j<4;j++){
                for(int k=0;k<2;k++){
                    map[y+j][x+k]=c;
                }
            }
        }
    }
}
int main(){
    while(cin >> w >> h,w){
    	ans="NG";
        cin >> xs >> ys >> xg >> yg >> n;
        for(int i=1;i<=h;i++){
            for(int j=1;j<=w;j++){
                map[i][j]=0;
            }
        }
        mc();
        start=map[ys][xs];
        if(map[ys][xs]==0||map[yg][xg]==0);
        else
        	fun(ys,xs);
        cout << ans << endl;
    }
}