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 <vector>
#include <map>
#include <set>
#include <stack>
#include <queue>
#include <algorithm>
#include <utility>
#include <functional>
#include <sstream>
#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <ctime>
#include <climits>
using namespace std;
inline int toInt(string s) { int v; istringstream sin(s); sin >> v; return v;}
template<class T> inline string toStr(T x) { ostringstream sout; sout << x; return sout.str();}
typedef vector<int> vi;
typedef vector<vi>  vvi;
typedef vector<string> vs;
typedef pair<int, int> pii;
typedef long long ll;
#define ALL(a) (a).begin(),(a).end()
#define RALL(a) (a).rbegin(),(a).rend()
#define FOR(i,a,b) for(int i=(a);i<=(b);++i)
#define REP(i,n) FOR(i,0,(n)-1)
const double EPS = 1e-12;
const double PI = acos(-1.0);
const int INF = INT_MAX/10;

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

struct state {
	int x, y;
	state(int x, int y) : x(x), y(y) {};
};

int main() {
	int w, h;
	while(cin >> w >> h, w) {
		vvi field(h+1, vi(w+1));
		vvi visit(h+1, vi(w+1));
		
		int xs, ys, xg, yg, n;
		cin >> xs >> ys >> xg >> yg >> n;

		int c, d, x, y;
		REP(i, n) {
			cin >> c >> d >> x >> y;
			REP(j, 4) {
				REP(k, 2) {
					if(d) {
						field[y+j][x+k] = c;
					} else {
						field[y+k][x+j] = c;
					}
				}
			}
		}

		stack<state> S;
		S.push(state(xs, ys));
		int color = field[ys][xs];
		bool goal = false;
		while(!S.empty()) {
			state st = S.top();
			S.pop();

			if(st.x == xg && st.y == yg) {
				goal = true;
				break;
			}

			int nx, ny;
			REP(d, 4) {
				nx = st.x + dx[d];
				ny = st.y + dy[d];
				if(0<=nx && nx<w && 0<=ny && ny<h) {
					if(!visit[ny][nx] && field[ny][nx] == color) {
						visit[ny][nx] = 1;
						S.push(state(nx, ny));
					}
				}

			}
		}

		if(color == 0) {
			goal = false;
		}

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

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

const int dx[] = {1, 0, -1, 0}, dy[] = {0, 1, 0, -1};
int w, h, board[101][101], xg, yg;
bool visited[101][101];

bool search(int x, int y, int c) {
    if (x == xg && y == yg) {
        return true;
    }
    visited[y][x] = true;
    for (int i = 0; i < 4; i++) {
        int px = x + dx[i], py = y + dy[i];
        if (px < 1 || w < px || py < 1 || h < py) continue;
        if (visited[py][px] || board[py][px] != c) continue;
        if (search(px, py, c)) return true;
    }
    return false;
}

int main() {
    int i, j, xs, ys, n, c, d, x, y;

    while (cin >> w >> h, w) {
        for (i = 1; i <= h; i++) {
            for (j = 1; j <= w; j++) {
                board[i][j] = 0;
                visited[i][j] = false;
            }
        }
        cin >> xs >> ys;
        cin >> xg >> yg;
        cin >> n;
        while (n--) {
            cin >> c >> d >> x >> y;
            int bw = d==0? 4: 2;
            int bh = 6 - bw;
            for (i = y; i < y+bh; i++) {
                for (j = x; j < x+bw; j++) {
                    board[i][j] = c;
                }
            }
        }

        if (board[ys][xs] == board[yg][xg] &&
            search(xs, ys, board[ys][xs])) {
            cout << "OK";
        }
        else {
            cout << "NG";
        }
        cout << endl;
    }
    return 0;
}

C++: #include<iostream>
#include<queue>
#include<list>

typedef struct block
{
	int x;
	int y;
	int h;
	int w;
	int color;
}block;

block blocks[1280];

std::queue<int> que;
std::list< std::pair<int,int> > adjacive;

void makelist(int n);
bool BFS(int start,int goal);

int main()
{
	int n,w,h,xs,ys,xg,yg,start,goal;
	while(1)
	{
		std::cin>>w>>h;
		if(w==0&&h==0)break;
		std::cin>>xs>>ys>>xg>>yg>>n;
		for(int i=0;i<n;i++)
		{
			int c,d,x,y;
			std::cin>>c>>d>>x>>y;
			blocks[i].color=c;
			blocks[i].x=x;
			blocks[i].y=y;
			if(d==0)
			{
				blocks[i].h=2;
				blocks[i].w=4;
			}
			else
			{
				blocks[i].h=4;
				blocks[i].w=2;
			}
			if(blocks[i].x<=xs&&blocks[i].x+blocks[i].w>=xs&&blocks[i].y<=ys&&blocks[i].y+blocks[i].h>=ys)
			{
				start=i;
			}
			else if(blocks[i].x<=xg&&blocks[i].x+blocks[i].w>=xg&&blocks[i].y<=yg&&blocks[i].y+blocks[i].h>=yg)
			{
				goal=i;
			}
		}
		makelist(n);
		if(BFS(start,goal))
		{
			std::cout<<"OK"<<std::endl;
		}
		else
		{
			std::cout<<"NG"<<std::endl;
		}
	}
	return 0;
}

void makelist(int n)
{
#define x1 blocks[i].x
#define y1 blocks[i].y
#define h1 blocks[i].h
#define w1 blocks[i].w
#define x2 blocks[j].x
#define y2 blocks[j].y
#define h2 blocks[j].h
#define w2 blocks[j].w

	for(int i=0;i<n;i++)
	{
		for(int j=i+1;j<n;j++)
		{
			if(blocks[i].color==blocks[j].color)
			{
				if((x1==x2+w2&&y1<=y2+h2&&y1+h1>=y2)||(x2==x1+w1&&y1<=y2+h2&&y1+h1>=y2)||(y1==y2+h2&&x1<=x2+w2&&x1+w1>=x2)||(y2==y1+h1&&x1<=x2+w2&&x2<=x1+w1))
				{
					adjacive.push_back(std::pair<int ,int>(i,j));
				}
			}
		}
	}
}

bool BFS(int start,int goal)
{
	int survey;
	que.push(start);
	
	
	while(!que.empty())
	{
		survey=que.front();
		que.pop();
		for(std::list< std::pair<int,int> >::iterator it=adjacive.begin();it!=adjacive.end();it++)
		{
			if(it->first==survey)
			{
				que.push(it->second);
			}
		}
		if(survey==goal)
		{
			return true;
		}
	}
	return false;
}