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<cstring>
#include<queue>
#include<map>
using namespace std;
int C,goal,n,x,y,xs,ys,xg,yg,mas[110][110]={{0}};
int dx[4]={0,0,1,1};
int dy[4]={0,1,0,1};
int d[110][110];
typedef pair<int,int>P;

int bfs();
int main(){

  while(1){
    goal=0;
    memset(mas,0,sizeof(mas));
    memset(d,0,sizeof(d));
    C = goal = n = x = y = xs = ys = xg = yg = 0;

    cin >> x >> y;//ボードの大きさ。 ※：x=横。y=縦。
    if(x==0 && y==0){
      break;
    }
    cin >> xs >> ys;//スタート地点。
    cin >> xg >> yg;//ゴール地点。
    cin >> n;//ブロックの数。
    
    //色染め。
    int color,dire,xx,yy;
    for(int t=0;t<n;t++){
      cin >> color >> dire >> xx >> yy;

      //横長。
      if(dire==0){
	for(int i=0;i<2;i++){
	  for(int j=0;j<4;j++){
	    mas[yy+i][xx+j]=color;
	  }
	}
      }
      
      //縦長。
      else{
	for(int i=0;i<4;i++){
	  for(int j=0;j<2;j++){
	    mas[yy+i][xx+j]=color;
	  }
	}
      }
      
    }
    
    //通る色　摘出。
    C=mas[ys][xs];
    //cout << "color:" << C << endl;
    
    if(C!=0){

      bfs();

    
      if(goal==1){
	cout << "OK" << endl;
	goal=0;
      }
      else{
	cout << "NG" << endl;
      }
    }
    else{
      cout << "NG" << endl;
    }
  }
}

int bfs(){
  queue<P>que;
  memset(d,-1,sizeof(d));
  que.push(P(ys,xs));
  d[ys][xs]=0;
  while(!que.empty()){
    P p=que.front();
    que.pop();
    if(p.first==yg && p.second==xg){
      goal=1;
      break;
    }
    for(int i=0;i<4;i++){
      int ny=p.first+dy[i];
      int nx=p.second+dx[i];
      if(ny>=1 && ny<=y && nx>=1 && nx<=x && mas[ny][nx]==C && d[ny][nx]==-1){
	d[ny][nx] = 1;
	que.push(P(ny,nx));
      }
    }
  }
  return (0);
}

C++: #include <iostream>
#include <cstring>
using namespace std;
bool b;
int dx[]={1,0,-1,0};
int dy[]={0,1,0,-1};
int board[110][110];

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

C++: #include<iostream>
using namespace std;
#define MAX 100

int map[MAX][MAX];
int xs, ys, xg, yg;
int n;
int w, h;
int c, d, x, y;
int count = 0;
int color;
int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};

void jadge(int x, int y){
	if(0 <= x && x < w && 0 <= y && y < h && map[x][y] == color && count == 0){
		if(x == xg && y == yg){
			count = 1;
			return;
		}
		for(int i=0; i < 4; i++){
			jadge(x+dx[i], y+dy[i]);
		}
	}
}
int main(){
	while(1){
		count = 0;

		for(int i=0; i < MAX; i++){
			for(int j=0; j< MAX; j++){
				map[i][j] = 0;
			}
		}

		cin >> w >> h;
		if(w == 0 && h == 0) break;

		cin >> xs >> ys;
		cin >> xg >> yg;
		xs--; ys--; xg--; yg--;
		cin >> n;
		for(int i=0; i < n; i++){
			cin >> c >> d >> y >> x;

			for(int i=0;  i < 4; i++){
				for(int j=0; j < 2; j++){
					if(d == 1){
						map[x-1+i][y-1+j] = c;
					}
					else{
						map[x-1+j][y-1+i] = c;
					}
				}
			}
		}
		if(map[xs][ys] != map[xg][yg]){
			cout << "NG" << endl;
			continue;
		}
		else if(map[xs][ys] == 0 || map[xg][yg] == 0){
			cout << "NG" << endl;
			continue;
		}
		color = map[xs][ys];

		jadge(xs, ys);

		if(count == 1) cout << "OK" << endl;
		else cout << "NG" << endl;
	}
}