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 <utility>
using namespace std;

typedef pair<int,int> P;

#define REP(i,b,n) for(int i=b;i<n;i++)
#define rep(i,n) REP(i,0,n)

const int dy[4] = {-1, 1, 0, 0};
const int dx[4] = {0, 0, -1, 1};
const int MAX_W = 101, MAX_H = 101;
int maze[MAX_H][MAX_W];
int w, h, xs, ys, xg, yg, color;

void solve() {
  memset(maze, 0, sizeof maze);
  int n;
  cin>>xs>>ys>>xg>>yg>>n;
  rep(i,n) {
    int c, d, x, y;
    cin>>c>>d>>x>>y;
    //cout<<c<<d<<x<<y<<endl;
    if (d == 0) {
      REP(j,x,x+4) REP(k,y,y+2) maze[k][j] = c;
    } else {
      REP(j,x,x+2) REP(k,y,y+4) maze[k][j] = c;
    }
  }
  
  if (maze[ys][xs] == 0) {
    cout<<"NG"<<endl;
    return;
  } else {
    color = maze[ys][xs];
  }
  
  bool flag = false;
  queue<P> que;
  que.push(P(xs, ys));
  while (!que.empty() || !flag) {
    P p = que.front(); que.pop();
    int tx = p.first, ty = p.second;
    if (tx == xg && ty == yg) {
      flag = true; continue;
    }
    if (maze[ty][tx] == 0) continue;
    maze[ty][tx] = 0;
    
    rep(z,4) {
      int ttx = tx + dx[z], tty = ty + dy[z];
      if (ttx < 1 || tty < 1 || ttx >= w || tty >= h) continue;
      if (maze[tty][ttx] != color) continue;
      que.push(P(ttx, tty));
    }
  }
  
  if (flag) {
    cout<<"OK"<<endl;
  } else {
    cout<<"NG"<<endl;
  }
}

int main (int argc, char const* argv[]) {
  while (cin>>w>>h, w||h) {
    solve();
  }
  return 0;
}

C++: #include<stdio.h>
#include<windows.h>
int main(void)
{
	int w,h;
	int map[101][101];
	int st[2],go[2];
	int i,j,k,l,m;
	int num;
	int b_c,b_ang,b_x,b_y;
	int sign;
	int ans;
	int maps=0;
	
	for(;;)
	{
		ans=0;
		
		for(i=0;i<100;i++)
		{
			for(j=0;j<100;j++)
				map[i][j]=0;
		}
		
		scanf("%d%d",&w,&h);
		
		if(w==0 && h==0)
			break;
		
		scanf("%d%d%d%d",&st[0],&st[1],&go[0],&go[1]);
		
		
		scanf("%d",&num);
		
		for(i=0;i<num;i++)
		{
			scanf("%d%d%d%d",&b_c,&b_ang,&b_x,&b_y);
			
			if(b_ang==0)
			{
				for(j=0;j<4;j++)
				{
					for(k=0;k<2;k++)
						map[b_x+j][b_y+k]=b_c;
				}
			}
			else
			{
				for(j=0;j<4;j++)
				{
					for(k=0;k<2;k++)
						map[b_x+k][b_y+j]=b_c;
				}
			}
		}
		
		if(map[st[0]][st[1]]==0 || map[go[0]][go[1]]==0)
			printf("NG");
		else
		{
			sign=map[st[0]][st[1]];
			
			for(i=0;i<w;i++)
			{
				for(j=0;j<h;j++)
				{
					if(map[i][j]!=sign)
						map[i][j]=0;
					else
						maps++;
				}
			}
			
			map[st[0]][st[1]]=-1;
			map[go[0]][go[1]]=-2;
			
			for(i=st[0],j=st[1];;)
			{
				
/*
				for(m=0;m<h;m++)
				{
					for(l=0;l<w;l++)
					{
						printf("%d ",map[l][m]);
					}
					printf("%dツ行\n",l);
				}
				getchar();
				system("cls");
*/
				
				if(map[i+1][j]==-2 || map[i][j+1]==-2 || map[i-1][j]==-2 || map[i][j-1]==-2)
				{
					ans=1;
					break;
				}
				else if(map[i-1][j]!=0 && map[i][j-1]!=0 && map[i+1][j]!=0 && map[i][j+1]!=0)
				{
					if(map[i+1][j]==sign)
					{
						map[i][j]=7;
						i++;
						maps--;
					}
					else if(map[i][j+1]==sign)
					{
						map[i][j]=7;
						j++;
						maps--;
					}
					else if(map[i-1][j]==sign)
					{
						map[i][j]=7;
						i--;
						maps--;
					}
					else if(map[i][j-1]==sign)
					{
						map[i][j]=7;
						j--;
						maps--;
					}
				}
				else if(map[i+1][j]==sign/* && map[i][j-1]!=sign*/)//ツ右
				{
//					printf("migi\n");
					map[i][j]=7;
					i++;
					maps--;
				}
				else if(/*map[i+1][j]!=sign && */map[i][j+1]==sign)//ツ可コ
				{
//					printf("sita1\n");
					map[i][j]=7;
					j++;
					maps--;
				}
				else if(map[i-1][j]==sign/* && map[i][j+1]!=sign*/)//ツ債カ
				{
//					printf("hidari\n");
					map[i][j]=7;
					i--;
					maps--;
				}
				else if(/*map[i+1][j]!=sign && */map[i][j-1]==sign)//ツ湘」
				{
//					printf("ue1\n");
					map[i][j]=7;
					j--;
					maps--;
				}
				else if(/*map[i-1][j]!=sign && */map[i][j+1]==sign)//ツ可コ
				{
//					printf("sita2\n");
					map[i][j]=7;
					j++;
					maps--;
				}
				else if(map[i-1][j]!=sign && map[i][j-1]==sign)//ツ湘」
				{
//					printf("ue2\n");
					map[i][j]=7;
					maps--;
					j--;
				}
				else if(map[i+1][j]!=sign && map[i][j+1]!=sign && map[i-1][j]!=sign && map[i][j-1]!=sign && maps==0)
				{
					ans=2;
					break;
				}
				else
				{
					
					map[i][j]=7;
					
					for(m=0;m<h;m++)
					{
						for(l=0;l<w;l++)
						{
							if((map[m][l]==sign && map[m][l+1]==7) || (map[m][l]==sign && map[m-1][l]))
							{
								i=m;
								j=l;
							}
						}
					}
				}
			}
			if(ans==1)
				printf("OK");
			else if(ans==2)
				printf("NG");
		}
	}
}
/*
20 20 
1 1
2 7
7
2 0 1 1
5 1 1 3
2 1 3 3
1 1 5 2
5 1 7 3
2 0 2 7
2 0 6 8
*/