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<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(105, vector<int>(105, 0));
vector <vector<bool > > grid_visited(105, vector<bool>(105, false));
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
		{
			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;
			}*/
			grid = vector<vector<int> >(105, vector<int>(105, 0));
			grid_visited = vector <vector<bool > > (105, vector<bool>(105, false));
			a = false;

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

}#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(105, vector<int>(105, 0));
vector <vector<bool > > grid_visited(105, vector<bool>(105, false));
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
		{
			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;
			}*/
			grid = vector<vector<int> >(105, vector<int>(105, 0));
			grid_visited = vector <vector<bool > > (105, vector<bool>(105, false));
			a = false;

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

}

C++: #include <iostream>
#include <vector>
#include <algorithm>
#include <queue>
using namespace std;
#define INF 1010001000
#define loop(i, n) for (int i = 0; i < n; i++)
#define mp make_pair
typedef pair<int, int> i_i;

bool dfs(vector<vector<int> > &g);

int sx, sy, gx, gy;
int n, m; 
int dx[4]={0,1,0,-1};
int dy[4]={1,0,-1,0};

int main()
{

while(cin >> n >> m,(n|m)){
 m++; n++;
 vector<vector<int> > graph(m,vector<int>(n,0));
 
 cin>>sx>>sy>>gx>>gy;
 int bl;  cin>>bl;
 loop(i, bl){
  int a,b,c,t; cin>>a>>b>>c>>t;
  if(!b){
   for(int j=t;j<t+2;j++){
    for(int k=c;k<c+4;k++){
     graph[j][k] = a;
    }
   } 
  } else {
   for(int j=c;j<c+2;j++){
    for(int k=t;k<t+4;k++){
     graph[j][k] = a;
    }
   }
  }
 }
cout << ((dfs(graph)) ? "OK" : "NG") << endl;
}
return 0;
}

bool dfs(vector<vector<int> > &g) {
int cl = g[sy][sx];
vector<vector<bool> > vsed(m,vector<bool>(n,false));
queue<i_i > q;
q.push(mp(sx,sy));
while(!q.empty()){
int x = q.front().first, y = q.front().second;
q.pop();
if(x == gx && y == gy){
return true;
}
if(vsed[y][x]){
continue;
} else {
vsed[y][x]=true;
}

loop(i, 4) {
int nx = x +dx[i], ny = y +dy[i];
if(0<nx && nx < n && 0<ny && ny < m){
if(g[ny][nx] == cl){
q.push(mp(nx,ny));
}
} 
}

}
return false;
}