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>

using namespace std;

int w,h;
int map[101][101];
int xg,yg;

int dx[]={1,-1,0,0};
int dy[]={0,0,1,-1};
void mapout()
{
  for(int xx=0;xx<h;xx++,cout<<endl)
    for(int yy=0;yy<w;yy++)
      if(map[xx][yy]!=-1)
      cout<<map[xx][yy];
      else
	cout<<"X";
}

bool check(int x,int y)
{
  //  cout<<"check "<<x<<" "<<y<<";"<<map[x][y]<<endl;
  if(x==xg&&y==yg)
    return true;
  int buf=map[x][y];
  map[x][y]=-1;
  for(int i=0;i<4;i++)
    {
      if(x+dx[i]>=0&&x+dx[i]<h&&
	 y+dy[i]>=0&&y+dy[i]<w&&
	 buf==map[x+dx[i]][y+dy[i]] &&
	 map[x+dx[i]][y+dy[i]]!=-1 &&
	 check(x+dx[i],y+dy[i]))
	return true;
    }

  
  return false;
}

int main()
{
  for(;cin>>w>>h,w;)
    {
      memset(map,-1,sizeof(map));
      int xs,ys;
      cin>>xs>>ys;
      cin>>xg>>yg;
      xs--;ys--;
      xg--;yg--;
      
      int n;
      cin>>n;
      for(;n--;)
	{
	  int c,d,x,y;
	  cin>>c>>d>>y>>x;
	  x--;y--;
	  if(d==0)
	    {
	      for(int xx=x;xx<x+2;xx++)
		for(int yy=y;yy<y+4;yy++)
		  map[xx][yy]=c;
	    }
	  else
	    {
	      for(int xx=x;xx<x+4;xx++)
		for(int yy=y;yy<y+2;yy++)
		  map[xx][yy]=c;
	    }
	}
      ///   mapout();
      if(check(xs,ys))
	cout<<"OK"<<endl;
      else 
	cout<<"NG"<<endl;
    }
  
  

}

C++: #include <iostream>
using namespace std;
   
int F[102][102];
int xg,yg,w,h;
   
   
void DFS(int Y,int X,int c){
  //if(Y < 1 || X < 1)
    //return;
  if(F[Y][X] != c){
    return;
  }
   
  F[Y][X] = -1;
  DFS(Y+1,X  ,c);
  DFS(Y-1  ,X,c);
  DFS(Y,X+1  ,c);
  DFS(Y  ,X-1,c);
}
   
   
int main(){
  int xs,ys,n;
  while(1){
    cin >> w >> h;
    if(w == 0 && h == 0)
      break;
for(int i=0; i<103; i++){
      for(int j=0; j<103; j++){
        F[i][j] = 10;
      }
    }
       F[0][104] = 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(c == 0)
         c = 1919810;
      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(F[xg][yg] == -1){
    cout << "OK" << endl;
  } else {
    cout << "NG" <<endl;
  }
  }
}

C++: #include<stdio.h>
int w,h;
int is(int x,int y){
	return (x>=0 && x < w && y>=0 && y< h);
}
int main(void){
	const int dx[4]={0,1,0,-1};
	const int dy[4]={1,0,-1,0};
	int qx[100000];
	int qy[100000];
	int p,mx;
    int n,m[101][101]={0};
    int xs,ys,xg,yg,a,c,d,x,y,cnt,f;
	for(;;){
		scanf("%d %d",&w,&h);
		//printf("%d %d\n",w,h);
		if(w==0)break;
		for(int i=0;i<w;i++){
			for(int j=0;j<h;j++){
				m[i][j]=0;
			}
		}
		scanf("%d %d %d %d",&xs,&ys,&xg,&yg);
		scanf("%d",&n);
		for(int i=0;i<n;i++){
			scanf("%d %d %d %d",&c,&d,&x,&y);
			for(int j=0;j<(d==0?2:4);j++){
				for(int k=0;k<(d==0?4:2);k++){
					m[x-1+k][y-1+j]=c;
				}
			}
		}
		c = m[xs-1][ys-1];
		p=0;
		mx=1;
		qx[0]=xs-1;
		qy[0]=ys-1;
		f=c!=0;
/*
		for(int i=0;i<h;i++){
			for(int j=0;j<w;j++){
				printf("%d ",m[j][i]);
			}
			puts("");
		}
				printf("%d\n",c);*/
		while(!f && p<mx){
			cnt = 0;
			for(int i=0;i<4;i++){
				x = qx[p] + dx[i];
				y = qy[p] + dy[i];
				if(is(x,y) && m[x][y] == c){
					m[x][y]=-1;
					cnt++;
					qx[p+cnt] = x;
					qy[p+cnt] = y;
					if(x == xg-1 && y == yg-1)f=1;
				}
			}
			mx += cnt;
			p++;
		}
		puts(f?"OK":"NG");
	}
    return 0;
}

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

struct board{
  int mass[102][102];
};

bool goal_flag;
void DFS(int x,int y,int gx,int gy,board b,int c){
    if(b.mass[y][x]!=c)return;
    if(!b.mass[y][x])return;
    b.mass[y][x]=-1;
    if(x==gx&&y==gy)goal_flag=true;
    DFS(x+1,y,gx,gy,b,c);
    DFS(x-1,y,gx,gy,b,c);
    DFS(x,y+1,gx,gy,b,c);
    DFS(x,y-1,gx,gy,b,c);
}

int main(){
  int h,w;
  int start_x,start_y;
  int goal_x,goal_y;
  int n;
  int c,d,x,y;
  while(1){
    cin>>w>>h;
    if(w==0&&h==0)break;
    cin>>start_x>>start_y;
    cin>>goal_x>>goal_y;
    cin>>n;

    board b;
    for(int i=0;i<h+2;i++){
      for(int j=0;j<w+2;j++){
        b.mass[i][j]=0;
      }
    }

    for(int i=0;i<n;i++){
        cin>>c>>d>>x>>y;
        for(int j=0;j<2;j++){
          for(int k=0;k<4;k++){
            if(d==0){b.mass[y+j][x+k]=c;}
            else if(d==1){b.mass[y+k][x+j]=c;}
          }
        }
    }
    goal_flag=false;
    DFS(start_x,start_y,goal_x,goal_y,b,b.mass[start_y][start_x]);
    if(goal_flag)cout<<"OK";
    else cout<<"NG";
    cout<<endl;
  }
}

C++: #include<bits/stdc++.h>
#define INF 1e9
using namespace std;
typedef pair<int,int> P;

int main(){
	int w,h;
	while(cin>>w>>h,w,h){
		char board[114][514];
		int pass[114][514];
		
		int xs,ys,xg,yg;
		cin>>xs>>ys>>xg>>yg;
		
		for(int i=0;i<=w;i++){
		for(int j=0;j<=h;j++){pass[i][j]=INF;
			board[i][j]='#';
			}}
		int n;
		cin>>n;
		for(int i=0;i<n;i++){
			char a;
			int b,c,d;
			cin>>a>>b>>c>>d;
			
			if(b==0){
				for(int j=0;j<2;j++)
				for(int k=0;k<4;k++)board[d+j][c+k]=a;
				}
			else{
				for(int j=0;j<2;j++)
				for(int k=0;k<4;k++)board[d+k][c+j]=a;
				}	
			}
		
		queue<P>Q;
		Q.push(P(ys,xs));
		pass[ys][xs]=0;
		
		while(Q.size()){
			P p=Q.front();
			Q.pop();
			
			if(p.first==yg&&p.second==xg)break;
			
			int dir[2][4]={{1,0,-1,0},{0,1,0,-1}};
			for(int i=0;i<4;i++){
				int ny=p.first+dir[0][i];
				int nx=p.second+dir[1][i];
				
				if(0<=ny&&ny<=h&&0<=nx&&nx<=w&&board[ny][nx]==board[ys][xs]){
					Q.push(P(ny,nx));
					pass[ny][nx]=pass[p.first][p.second]+1;
					}
				}
			}
		
		if(pass[yg][xg]!=INF)cout<<"OK"<<endl;
		else cout<<"NG"<<endl;
		
		}
		return 0;
	}