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>
using namespace std;
struct cordinate{
        int y;
        int x;
};
cordinate SIZE,Start,Goal;
struct Blocks{
        int color;
        int direction;
        int y;
        int x;
};
Blocks block[200];
int N,board[200][200];
int Color,dp[200][200];
int recursion(int y,int x){
        int res=0;
        if(board[y][x]==0)
                return false;
        if(y==Goal.y && x==Goal.x){
                return true;
        }
        else{
                board[y][x]=0;
                if(recursion(y+1,x))return true;
                if(recursion(y-1,x))return true;
                if(recursion(y,x+1))return true;
                if(recursion(y,x-1))return true;
        }
        return false;
}
int main(){
        while(true){
                for(int i=0 ; i<100 ; i++ )
                        for(int j=0 ; j<100 ; j++ ){
                                dp[i][j]=-1;
                                board[i][j]=0;
                        }
                cin >> SIZE.x >> SIZE.y;
                if(SIZE.x+SIZE.y==0)
                        break;
                cin >> Start.x >> Start.y;
                cin >> Goal.x >> Goal.y;
                cin >> N;
                for(int i=0 ; i<N ; i++ ){
                        cin >> block[i].color >> block[i].direction;
                        cin >> block[i].x >> block[i].y;
                        if(block[i].direction){
                                for(int l=block[i].y ; l<block[i].y+4 ; l++ ){
                                        for(int j=block[i].x ; j<block[i].x+2 ; j++ ){
                                                board[l][j]=block[i].color;
                                        }
                                }
                        }
                        else{
                                for(int l=block[i].y ; l<block[i].y+2 ; l++ ){
                                        for(int j=block[i].x ; j<block[i].x+4 ; j++ ){
                                                board[l][j]=block[i].color;
                                        }
                                }
                        }
                }
                Color=board[Start.y][Start.x];
                if(recursion(Start.y,Start.x)>0)
                        cout <<"OK"<<endl;
                else
                        cout <<"NG"<<endl;
        }
        return 0;
}

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

struct board{
  int mass[102][102]={0};
};

bool goal_flag;
void DFS(int x,int y,int gx,int gy,board b,int c){
    if(b.mass[y][x]!=c)return;
    if(!b.mass[y][x])return;
    b.mass[y][x]=-1;
    if(x==gx&&y==gy)goal_flag=true;
    DFS(x+1,y,gx,gy,b,c);
    DFS(x-1,y,gx,gy,b,c);
    DFS(x,y+1,gx,gy,b,c);
    DFS(x,y-1,gx,gy,b,c);
}

int main(){
  int h,w;
  int start_x,start_y;
  int goal_x,goal_y;
  int n;
  int c,d,x,y;
  while(1){
    cin>>w>>h;
    if(w==0&&h==0)break;
    cin>>start_x>>start_y;
    cin>>goal_x>>goal_y;
    cin>>n;

    board b;


    for(int i=0;i<n;i++){
        cin>>c>>d>>x>>y;
        for(int j=0;j<2;j++){
          for(int k=0;k<4;k++){
            if(d==0){b.mass[y+j][x+k]=c;}
            else if(d==1){b.mass[y+k][x+j]=c;}
          }
        }
    }
    goal_flag=false;
    DFS(start_x,start_y,goal_x,goal_y,b,b.mass[start_y][start_x]);
    if(goal_flag)cout<<"OK";
    else cout<<"NG";
    cout<<endl;
  }
}

C++: #include<cstdio>
#include<iostream>
#include<algorithm>
#include<string>
#include<queue>
#include<vector>
#include<functional>
#include<cmath>
#include<map>
#include<stack>
#include<set>
#include<numeric>
#include<limits>

#define all(x) (x).begin(),(x).end()
#define rall(x) (x).rbegin(),(x).rend()

using namespace std;
typedef long long ll;
typedef pair<int, int> pi;
typedef pair<ll, ll> pl;
typedef pair<ll, char> plc;

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

int check(int xs, int ys, int xg, int yg ,int c, int board[110][110]) {
	int used[110][110] = { 0 };
	queue<pl> q;
	q.push({ xs, ys });

	while (!q.empty()) {
		int x = q.front().first;
		int y = q.front().second;
		q.pop();
		for (int i = 0; i < 4; i++) {
			int ddx = dx[i] + x;
			int ddy = dy[i] + y;
			if (ddx >= 1 && ddx <= w && ddy >= 1 && ddy <= h && !used[ddy][ddx]) {
				used[ddy][ddx] = 1;
				if (board[ddy][ddx] == c && ddy == yg && ddx == xg)return 1;
				else if (board[ddy][ddx] == c) {
					q.push({ddx,ddy});
				}
			}
		}
	}
	return 0;
}

int main()
{
	while (cin >> w >> h, w, h) 
	{
		int xs, ys, xg, yg;
		int n;
		int board[110][110] = { 0 };
		cin >> xs >> ys >> xg >> yg;
		cin >> n;
		for (int i = 0; i < n; i++)
		{ 
			int c,d, x, y;
			cin >> c >> d >> x >> y;
			if (!d){
				for (int i = y; i < y+2; i++) {
					for (int j = x; j < x+8; j++) 
						board[i][j] = c;
				}
			}
			else {
				for (int i = y; i < y+8; i++) {
					for (int j = x; j < x+2; j++)
						board[i][j] = c;
				}
			}
		}
		if (check(xs, ys, xg, yg, board[ys][xs], board))
			cout << "OK" << endl;
		else
			cout << "NG" << endl;
	}
	return 0;
}