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 <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;

int dy[] = {-1, 0, 0, 1};
int dx[] = {0, -1, 1, 0};
int w, h;
pii s, g;
int n;
int f[110][110];

int main() {
  cin.tie(0);
  ios_base::sync_with_stdio(false);
  cout << fixed << setprecision(10);
  
  while (cin >> w >> h, w) {
    cin >> s.second >> s.first;
    s.second--, s.first--;
    cin >> g.second >> g.first;
    g.second--, g.first--;    
    cin >> n;
    for (int i = 0; i < n; i++) {
      int c, d, x, y;
      cin >> c >> d >> x >> y;
      x--, y--;
      if (d == 0) {
        for (int j = 0; j < 2; j++) {
          for (int k = 0; k < 4; k++) {
            f[y + j][x + k] = c;
          }
        }
      } else {
        for (int j = 0; j < 4; j++) {
          for (int k = 0; k < 2; k++) {
            f[y + j][x + k] = c;
          }
        }
      }
    }
    if (f[s.first][s.second] == 0) {
      cout << "NG" << endl;
      continue;
    }
    bool used[110][110] = {};
    used[s.first][s.second] = true;
    queue<pii> que;
    que.emplace(s);
    while (!que.empty()) {
      pii u = que.front(); que.pop();
      int y = u.first, x = u.second;
      for (int i = 0; i < 4; i++) {
        int ny = y + dy[i], nx = x + dx[i];
        if (ny >= 0 && ny < h && nx >= 0 && nx < w && f[ny][nx] == f[y][x] && !used[ny][nx]) {
          used[ny][nx] = true;
          que.emplace(ny, nx);
        }
      }
    }
    cout << (used[g.first][g.second] ? "OK" : "NG") << endl;
  }

  return 0;
}

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;
		}
	}

}

C++: #include <bits/stdc++.h>
using namespace std;

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

void dfs(int x , int y){
	if(x==xg&&y==yg) {b=true;return;}
	for(int i=0;i<4;++i){
		int tx=x+dx[i];
		int ty=y+dy[i];
		if(tx<0||ty<0||tx>=w||ty>=h) continue;
		if(board[tx][ty]!=sc || board[tx][ty]==0) continue;
		if(b) continue;
		dfs(tx,ty);
	}
}

int main(){
	while(cin >> w >> h , w||h){
		int xs , ys;
		int n;
		b=false;
		//memset(board,0,sizeof(board));
		for(int i=0;i<101;++i){
			for(int j=0;j<101;++j){
				board[j][i]=0;
			}
		}
		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 k=0;k<2;++k){
					for(int j=0;j<4;++j){
						board[x+j][y+k]=c;
					}
				}
			} else if(d==1){
				for(int k=0;k<4;++k){
					for(int j=0;j<2;++j){
						board[x+j][y+k]=c;
					}
				}
			}
		}
		sc=board[xs][ys];
		int gc=board[xg][yg];
		if(sc!=gc) {}
		else dfs(xs,ys);
		cout << ( b ? "OK" : "NG") << endl;
	}
	return 0;
}