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;
int w, h, xs, ys, xg, yg, stage[101][101];
int ny[4] = { 0, 1, 0, -1 }, nx[4] = { 1, 0, -1, 0 };
int bc;
bool ans = false;
void func(int x, int y, int lastp){
	if (x == xg && y == yg){
		ans = true;
	}
	for (int i = 0; i < 4; i++){
		if (stage[y + ny[i]][x + nx[i]] != bc || i == lastp) return;
		func(x + nx[i], y + ny[i], (i + 2) % 4);
	}
}
int main(){
	int n, c, d, x, y, bw, bh;
	while (1){
		for (int i = 0; i < 101; i++){
			for (int j = 0; j < 101; j++){
				stage[i][j] = 0;
			}
		}
		cin >> w >> h;
		if (w == 0 && h == 0) return 0;
		cin >> xs >> ys >> xg >> yg >> n;
		for (int i = 0; i < n; i++){
			cin >> c >> d >> x >> y;
			if (d == 0){
				bw = 4;
				bh = 2;
			}
			else{
				bw = 2;
				bh = 4;
			}
			for (int j = 0; j < bh; j++){
				for (int k = 0; k < bw; k++){
					stage[y + j][x + k] = c;
				}
			}
		}
		bc = stage[ys][xs];
		if (bc == 0){
			cout << "NG\n";
			continue;
		}
		func(ys, xs, -1);
		if (ans == true) cout << "OK\n";
		else cout << "NG\n";
	}
	return 0;
}

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

int F[102][102];


int DFS(int Y,int X,int c){
  int cnt = 0;
  if(F[Y][X] != c){
    return 0;
  }

  F[Y][X] = -1;
  cnt += DFS(Y-1,X  ,c);
  cnt += DFS(Y  ,X+1,c);
  cnt += DFS(Y+1,X  ,c);
  cnt += DFS(Y  ,X-1,c);
  return cnt;
}


int main(){
  int w,h,xs,ys,xg,yg,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]=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 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(1){
    cout << "OK" << endl;
  } else {
    cout << "NG" << endl;
  }
  }
}

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



typedef vector<vector<int> > Matrix;
int w,h,xs,ys,xg,yg,n,flag;
string res = "NG";

class Block{
public:
  int color;
  int direction;
  int x,y,dx,dy;
  void write(Matrix &board){
    if(direction == 0)
      dx = 4,dy = 2;
    else if(direction == 1)
      dx = 2,dy = 4;
    for(int i=0; i<dx; ++i){
      for(int j=0; j<dy; ++j){
	(board.at(x+i)).at(y+j) = color;
      }
    }
  }
};
  
void func(Matrix &board,int nx,int ny){
  if(board[nx][ny] == 0){
    res = "NG";
    return;
  }
  if( nx==xg && ny==yg){
    res = "OK";
    return;
  }
  int temp = board[nx][ny];
  board[nx][ny] = 0;
  if( 0<=nx-1 && temp==board[nx-1][ny])
    func(board,nx-1,ny);
  if( 0<=ny-1 && temp==board[nx][ny-1])
    func(board,nx,ny-1);
  if( nx+1<=w && temp==board[nx+1][ny])
    func(board,nx+1,ny);
  if( ny+1<=h && temp==board[nx][ny+1])
    func(board,nx,ny+1);
}


int main(void){

  while(1){
    cin >> w >> h;
    if( w==0 && h==0) return 0;
    cin >> xs >> ys >> xg >> yg >> n;
    xs--; ys--; xg--; yg--;
    Block *object;
    object = new Block[n];
    Matrix board(w, vector<int>(h,0));
    for(int i=0; i<n; ++i){
      cin >> object[i].color;
      cin >> object[i].direction;
      cin >> object[i].x;
      cin >> object[i].y;
      --object[i].x; --object[i].y;
      object[i].write(board);	    
    }
    func(board,xs,ys);
    cout << res << endl;
    flag = 0;
    delete[] object;
    board.clear();
  }
}

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

int cell[101][101];
int max_i, max_j;
int goal_i, goal_j;
bool ret;

void search(int i, int j, int c){
	if(i<1 || j<1 || i>max_i || j>max_j) return;
	if(cell[i][j]!=c) return;
	else cell[i][j] = 0;
	if(i==goal_i && j==goal_j){
		ret = true;
		return;
	}

	search(i+1, j, c);
	if(ret) return;
	search(i-1, j, c);
	if(ret) return;
	search(i, j+1, c);
	if(ret) return;
	search(i, j-1, c);
	return;
}

int main(){
	while(1){
		cin >> max_i >> max_j;

		if(!max_i && !max_j) break;

		int start_i, start_j;
		cin >> start_i >> start_j;
		cin >> goal_i >> goal_j;

		int n;
		cin >> n;

		for(int i=0;i<max_i;i++){
			for(int j=0;j<max_j;j++){
				cell[i][j] = 0;
			}
		}

		for(int k=0;k<n;k++){
			int c, vec, i, j;
			cin >> c >> vec >> i >> j;
			cell[i][j] = cell[i+1][j] = cell[i][j+1] = cell[i+1][j+1] = c;
			if(vec){
				cell[i][j+2] = cell[i][j+3] = cell[i+1][j+2] = cell[i+1][j+3] = c;
			}else{
				cell[i+2][j] = cell[i+3][j] = cell[i+2][j+1] = cell[i+3][j+1] = c;
			}
		}
		
		ret = false;
		if(cell[start_i][start_j]){
			search(start_i, start_j, cell[start_i][start_j]);
		}

		if(ret) cout << "OK" << endl;
		else cout << "NG" << endl;
	}
}