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>

int field[102][102];//y,x
bool flag;
int sx,sy,gx,gy,col;

void erase(){
	for(int i=0; i<102; i++)
		for(int j=0; j<102; j++)
			field[i][j] = 0;
}

void DFS(int x, int y){
	if(sx < gy)
		DFSr(x,y);
	else
		DFSl(x,y);
}

void DFSr(int x, int y){
	if(field[y][x] != col)
		return;
	if(x == gx && y == gy){
		flag = true;
		return;
	}
	DFSr(x+1, y);
	if(flag)
		return;
	DFSr(x, y+1);
	if(flag)
		return;
	DFSr(x, y-1);
	if(flag)
		return;
	DFSr(x-1, y);
}

void DFSl(int x, int y){
	if(field[y][x] != col)
		return;
	if(x == gx && y == gy){
		flag = true;
		return;
	}
	DFSl(x-1, y);
	if(flag)
		return;
	DFSl(x, y+1);
	if(flag)
		return;
	DFSl(x, y-1);
	if(flag)
		return;
	DFSl(x+1, y);
}

int main(){
	int n,c,d,bx,by;
	while(true){
		flag = false;
		erase();

		std::cin >> c >> d;
		if(!c && !d)
			return 0;

		std::cin >> sx >> sy;
		std::cin >> gx >> gy;

		std::cin >> n;
		for(int i=0; i<n; i++){
			std::cin >> c >> d >> bx >> by;
			if(d==0)
				for(int h=by; h<by+2; h++)
					for(int w=bx; w<bx+4; w++)
						field[h][w] = c;
			else
				for(int h=by; h<by+4; h++)
					for(int w=bx; w<bx+2; w++)
						field[h][w] = c;
		}

		col = field[gy][gx];
		DFS(sx, sy);
		if(flag)
			std::cout << "OK\n";
		else
			std::cout << "NG\n";
	}
}

C++: #include <bits/stdc++.h>
using namespace std;
  
// #define int long long
#define pb push_back
  
typedef long long ll;
typedef unsigned long long ull;
typedef vector<int> vi;
typedef vector<vector<int> > vii;
 
template <class X> void print(X Target){ cout << Target << '\n'; }

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

int w, h;
int xs, ys, xg, yg;
int mp[128][128];
bool check[128][128];

void dfs(int y, int x, int color)
{
  if (x < 1 || x > w || y < 1 || y > h) return;
  if (check[y][x]) return;
  check[y][x] = true;
  for (int i = 0; i < 4; i++){
    if (mp[y + dy[i]][x + dx[i]] == color){
      dfs(y + dy[i], x + dx[i], color);
    }
  }
}

signed main()
{
  ios::sync_with_stdio(false);
  int n;

  while (cin >> w >> h, w || h){
    memset(check, false, sizeof(check));
    memset(mp, 0, sizeof(mp));
    cin >> xs >> ys >> xg >> yg >> n;
    for (int i = 0; i < n; i++){
      int c, d, x, y;
      cin >> c >> d >> x >> y;
      if (d){
        for (int j = 0; j < 4; j++){
          for (int k = 0; k < 2; k++){
            mp[y + j][x + k] = c;
          }
        }
      }
      else {
        for (int j = 0; j < 2; j++){
          for (int k = 0; k < 4; k++){
            mp[y + j][x + k] = c;
          }
        }
      }
    }
    dfs(ys, xs, mp[ys][xs]);
    (check[yg][xg]) ? print("OK") : print("NG");
  }

  return (0);
}

C++: #include <iostream>
using namespace std;
  
int F[105][105];
int xg,yg,w,h;
  
  
void DFS(int Y,int X,int c){
  if(F[Y][X] != c){
    return;
  }
  
  F[Y][X] = -1;
  DFS(Y+1,X  ,c);
  DFS(Y-1  ,X,c);
  DFS(Y,X+1  ,c);
  DFS(Y  ,X-1,c);
}
  
  
int main(){
  int xs,ys,n;
  while(1){
    cin >> w >> h;
    if(w == 0 && h == 0)
      break;
for(int i=0; i<102; i++){
      for(int j=0; j<102; j++){
        F[i][j] = 10;
      }
    }
      
    cin >> xs >> ys >> xg >> yg >> n;
  
  
    for(int i=0;i<n;i++){
      int c,d,x,y;
      cin >> c >> d >> x >> y;

      if(d == 0){
        for(int j=0;j<4;j++){
          F[x+j][y] = c;
          F[x+j][y+1] = c;
        }
      } else {
        for(int j=0;j<4;j++){
          F[x][y+j] = c;
          F[x+1][y+j] = c;
        }
      }
    }
  DFS(xs,ys,F[xs][ys]);
  
  if(F[xg][yg] == -1){
    cout << "OK" << endl;
  } else {
    cout << "NG" <<endl;
  }
  }
}

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

int dx[4] = { 1, 0, -1, 0 };
int dy[4] = { 0, 1, 0, -1 };


class cordinate
{

public:
	int x;
	int y;

};

int main()
{
	while(1)
	{


		int w;
		int h;
		cin >> w >> h; 
		if(w == 0 && h == 0)
		{
			break;
		}
		int xs;
		int ys;
		cin >> xs >> ys;
		int xg;
		int yg;
		cin >> xg >> yg;
		int n;
		cin >> n;

		vector<vector<int >> vobj;

		for(int i = 0; i < h; i++)
		{
			vector<int> lineobj;
			for(int j = 0; j < w; j++)
			{

				lineobj.push_back(0);

			}
			vobj.push_back(lineobj);

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

			if(d == 0)
			{
				vobj[x][y] = c;
				vobj[x + 1][y] = c;
				vobj[x + 2][y] = c;
				vobj[x + 3][y] = c;
				vobj[x][y + 1] = c;
				vobj[x + 1][y + 1] = c;
				vobj[x + 2][y + 1] = c;
				vobj[x + 3][y + 1] = c;
			}
			else if(d == 1)
			{
				vobj[x][y] = c;
				vobj[x][y + 1] = c;
				vobj[x][y + 2] = c;
				vobj[x][y + 3] = c;
				vobj[x + 1][y] = c;
				vobj[x + 1][y + 1] = c;
				vobj[x + 1][y + 2] = c;
				vobj[x + 1][y + 3] = c;
			}
		}
		/*for(int i = 0; i < w - 1; i++)
		{
			for(int j = 0; j < h - 1; j++)
			{
				cout << vobj[i][j] << " ";
			}
			cout << endl;
		}*/
		int startColor;
		startColor = vobj[xs - 1][ys - 1];
		queue<cordinate> que;

		cordinate obj;
		obj.x = xg - 1;
		obj.y = yg - 1;
		que.push(obj);
		bool flag = false;
		while(1)
		{
			if(startColor == 0)
			{
				break;
			}
			cordinate buf;
			buf = que.front();
			que.pop();

			int bx;
			int by;
			bx = buf.x;
			by = buf.y;
			if(bx == xg - 1 && by == yg - 1)
			{
				flag = true;
				break;
			}
			for(int i = 0; i < 4; i++)
			{
				if(bx + dx[i] >= 0 && bx + dx[i] <= w - 1)
				{
					if(by + dy[i] >= 0 && by + dy[i] <= h - 1)
					{
						if(vobj[bx + dx[i]][by + dy[i]] == startColor)
						{
							cordinate newObject;
							newObject.x = bx + dx[i];
							newObject.y = by + dy[i];
							que.push(newObject);

						}
					}
				}
			}
			vobj[bx][by] = 0;

			if(que.size() == 0)
			{
				break;
			}
		}


		if(flag == true)
		{
			cout << "OK" << endl;
		}
		else{
			cout << "NG" << endl;
		}
	}




}