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<algorithm>
#include<cstring>
using namespace std;

int xs,ys,c,a[105][105],memo[105][105],ans,p,w,h;

int solve(int yg,int xg){

  if(a[yg][xg] != p) return 0;

  a[yg][xg] = -1;

  if(xs == xg && ys == yg) return ans = 1;

  else if(yg - 1 > 0 && a[yg-1][xg] == p) solve(yg-1,xg);
  else if(xg - 1 > 0 && a[yg][xg-1] == p) solve(yg,xg-1);
  else if(yg + 1 <= w && a[yg+1][xg] == p) solve(yg+1,xg);
  else if(xg + 1 <= h && a[yg][xg+1] == p) solve(yg,xg+1);
}

int main(){
  int xg,yg,n,d,x,y;

  while(true){
    cin >> w >> h;
    if(!w && !h) break;

    memset(a,0,sizeof(a));
    memset(memo,0,sizeof(memo));
    ans = 0;

    cin >> xs >> ys >> xg >> yg >> n;

    for(int i=0;i<n;i++){
      cin >> c >> d >> x >> y;

      if(d == 0){
	for(int i=y;i<y+2;i++){
	  for(int j=x;j<x+4;j++) a[i][j] = c;
	}
      }

      else if(d == 1){
	for(int i=y;i<y+4;i++){
	  for(int j=x;j<x+2;j++) a[i][j] = c;
	}
      }
    }

    p = a[yg][xg];
    solve(yg,xg);

    if(ans == 1)   cout << "OK" << endl;
    else if(ans == 0)cout << "NG" << endl;

  }
}

C++: #include<iostream>
#include<algorithm>
#include<vector>
#include<string>
#define ll long long
#define loop(i,n) for (int i = 0; i < n; i++)
#define loops(i,f,n) for (int i = (f); i < n; i++)
#define INF 100000000000000
#define sort(a) sort(a.begin(),a.end())
#define rsort(a) sort(a.rbegin(),a.rend())
using namespace std;
int w, h, sx, sy, gx, gy, n;
vector <vector<int > > grid;
vector <vector<bool > > grid_visited;
void input(int c, int d, int x, int y)
{
	if (d == 0)//yokonaga
	{
		loop(i, 2)
		{
			loop(j, 4)
			{
				grid[y + i][x + j] = c;
			}
		}
	}
	else//tatenaga
	{
		loop(i, 4)
		{
			loop(j, 2)
			{
				grid[y + i][x + j] = c;
			}
		}
	}
}
bool a = false;
bool dfs(int nx, int ny)
{
	if (nx == gx&&ny == gy)return true;
	if (nx < 0 || ny < 0 || nx >= h || ny >= w || grid[nx][ny] == 0 || grid_visited[nx][ny])return false;
	grid_visited[nx][ny] = true;
	if ((nx + 1) >= 0 && ny >= 0 && (nx + 1) < h && ny < w)if (grid[nx + 1][ny] == grid[nx][ny])a |= dfs(nx + 1, ny);
	if (nx >= 0 && (ny + 1) >= 0 && nx < h && (ny + 1) < w)if (grid[nx][ny + 1] == grid[nx][ny])a |= dfs(nx, ny + 1);
	if ((nx - 1) >= 0 && ny >= 0 && (nx - 1) < h && ny < w)if (grid[nx - 1][ny] == grid[nx][ny])a |= dfs(nx - 1, ny);
	if (nx >= 0 && (ny - 1) >= 0 && nx < h && (ny - 1) < w)if (grid[nx][ny - 1] == grid[nx][ny])a |= dfs(nx, ny - 1);
	//return (dfs(nx + 1, ny) || dfs(nx, ny + 1) || dfs(nx - 1, ny) || dfs(nx, ny - 1));
	return a;
	return false;
}
int main()
{
	while (1)
	{
		cin >> w >> h;
		if (!w && !h) break;
		else
		{
			grid = vector<vector<int> >(105, vector<int>(105, 0));
			grid_visited = vector <vector<bool > > (105, vector<bool>(105, false));
			cin >> sx >> sy >> gx >> gy >> n;
			sx--; sy--; gx--; gy--;
			loop(i, n)
			{
				int c, d, x, y;
				cin >> c >> d >> x >> y;
				x--; y--;
				input(c, d, x, y);
			}
			/*loop(i, h)
			{
			loop(j, w)
			{
			cout << grid[i][j] << " ";
			}
			cout << endl;
			}*/
			a = false;

			cout << (dfs(sx, sy) ? "OK" : "NG") << endl;
		}
	}

}

C++: #include <cstdio>
#include <cstdlib>
#include <cmath>
#include <climits>
#include <cfloat>
#include <map>
#include <utility>
#include <ctime>
#include <set>
#include <iostream>
#include <memory>
#include <string>
#include <vector>
#include <algorithm>
#include <functional>
#include <sstream>
#include <complex>
#include <stack>
#include <queue>
#include <cstring>
#include <numeric>
#include <cassert>
using namespace std;
static const double EPS = 1e-10;
typedef long long ll;
#define rep(i,n) for(int i=0;i<n;i++)
#define rev(i,n) for(int i=n-1;i>=0;i--)
#define all(a) a.begin(),a.end()
#define mp(a,b) make_pair(a,b)
#define pb(a) push_back(a)
#define SS stringstream
#define DBG1(a) rep(_X,sz(a)){printf("%d ",a[_X]);}puts("");
#define DBG2(a) rep(_X,sz(a)){rep(_Y,sz(a[_X]))printf("%d ",a[_X][_Y]);puts("");}
#define bitcount(b) __builtin_popcount(b)
#define EACH(i,c) for(typeof((c).begin()) i=(c).begin(); i!=(c).end(); ++i)

#define delete(a,n) a.erase(remove(all(a),n),a.end())
template<typename T, typename S> vector<T>& operator<<(vector<T>& a, S b) { a.push_back(b); return a; }
template<typename T> void operator>>(vector<T>& a, int b) {while(b--)if(!a.empty())a.pop_back();}
bool isprime(int n){ if(n<2)return false;  for(int i=2;i*i<=n;i++)if(n%i==0)return false;  return true;} 
ll b_pow(ll x,ll n){return n ? b_pow(x*x,n/2)*(n%2?x:1) : 1ll;}
string itos(int n){stringstream ss;ss << n;return ss.str();}

int t[200][200];
int gxx,gyy;
int dfs(int x,int y,int c){
	if( t[y][x] != c ) return false;
	if( y == gyy && x == gxx) {
		return true;
	}
	t[y][x] = 0;
	if( dfs(x+1,y,c) ) return true;
	if( dfs(x-1,y,c) ) return true;
	if( dfs(x+0,y-1,c) ) return true;
	if( dfs(x+0,y+1,c) ) return true;
	
	return false;

}
int main(){
	int w,h;
	while(cin >> w >> h && w ){
		memset(t,0,sizeof(t));
		int xs,ys,xg,yg;
		cin >> xs >> ys >> xg >> yg;
		gxx = xg;
		gyy = yg;
		int n;
		cin >> n;
		for(int _ = 0 ; _ < n ; _++){
			int c,d,x,y;
			cin >> c >> d >> x >> y;
			if(!d){
				rep(i,2)rep(j,4) t[y+i][x+j] = c;
			}else{
				rep(i,4)rep(j,2) t[y+i][x+j] = c;
			}
		}
		if( t[ys][xs] == 0 ){
			cout << "NG" << endl;
		}else{
			cout << (dfs(xs,ys,t[ys][xs])?"OK":"NG") << endl;
		}
		
	}
}