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<algorithm>
#include<cstring>
using namespace std;
bool N[102][102];
int map[102][102],R,ga,gb,w,h;
bool block(int ,int);
int main()
{
	int i,j,a,n,L,b,c,d,X=0,Y=0,x,y;
	cin>>w>>h;
	while(w!=0||h!=0){
		memset(map,0,sizeof(map));
		memset(N,0,sizeof(N));
		cin>>a>>b;
		cin>>ga>>gb;
		cin>>n;
		for(i=0;i<n;i++){
			cin>>c>>d>>x>>y;
			if(d){
				map[y][x]=c;
				map[y+1][x]=c;
				map[y+2][x]=c;
				map[y+3][x]=c;
				map[y][x+1]=c;
				map[y+1][x+1]=c;
				map[y+2][x+1]=c;
				map[y+3][x+1]=c;

			}
			else{
				map[y][x]=c;
				map[y+1][x+1]=c;
				map[y+1][x+2]=c;
				map[y+1][x+3]=c;
				map[y+1][x]=c;
				map[y][x+1]=c;
				map[y][x+2]=c;
				map[y][x+3]=c;

			}
		}
		R=map[b][a];
		if(R==map[gb][ga]){
			if(block(a,b)) cout<<"OK"<<endl;
		        else cout<<"NG"<<endl;
		}
		else cout<<"NG"<<endl;
		//for(i=0;i<h;i++){
			//for(j=0;j<w;j++){
			//	cout<<map[i][j];
			//}
				
	//		cout<<endl;
		//}
		cin>>w>>h;
	}
	return 0;
}
bool block(int b,int a)
{
	//if(f==1) return 1;
	N[b][a]=1;
	if(ga==a&&gb==b) return 1;
	if(a+1!=w){
		if(map[b][a+1]==R&&N[b][a+1]==0) return block(b,a+1);}
	if(b+1!=h){
		if(map[b+1][a]==R&&N[b+1][a]==0) return block(b+1,a);}
	if(a-1!=-1){
		if(map[b][a-1]==R&&N[b][a-1]==0) return block(b,a-1);}
	if(b-1!=-1){
		if(map[b-1][a]==R&&N[b-1][a]==0) return block(b-1,a);}
	return 0;
}

C++: #include<map>
#include<queue>
#include<cstdio>
#include<cstring>
#include<stdio.h>
#include<iostream>
#include<algorithm>
#define SIZE 110
using namespace std;

typedef pair<int,int> P;

void solve(void);       //処理

int n;             //ブロックの個数
int w,h;           //ボードの幅、高さ
int goal;          //迷路になっているか
int scolor;        //スタート位置の色
int sx,sy,gx,gy;   //スタートの座標、ゴールの座標
int mass[SIZE][SIZE];
int data[SIZE][SIZE];
int dx[4]={1,0,-1,0};
int dy[4]={0,1,0,-1};
int c[SIZE],d[SIZE],x[SIZE],y[SIZE];       //ブロックの色、向き、左上の座標


int main(){

  int i,j;             //カウンタ変数

  while(1){

    goal=0;

    /*情報の入力*/
    cin>>w>>h;

    if(w==0 && h==0)break;
    
    cin>>sx>>sy;
    cin>>gx>>gy;  
    cin>>n;
    
    for(i=0;i<n;i++){
      cin>>c[i]>>d[i]>>x[i]>>y[i];
      
    }

  memset(mass,0,sizeof(mass));

  /*マスの作成*/
  for(i=0;i<n;i++){
    if(d[i]==0){       //横向きなら
      for(j=0;j<4;j++){
	mass[y[i]][x[i]+j]=c[i];
	mass[y[i]+1][x[i]+j]=c[i];
      }
    }
    else if(d[i]==1){              //縦向きなら
      for(j=0;j<4;j++){
	mass[y[i]+j][x[i]]=c[i];
	mass[y[i]+j][x[i]+1]=c[i];
      }
    }
  }
  
  scolor=mass[sy][sx];

  if(scolor==mass[gy][gx]){
  
    solve();
     
    if(goal==1){
      cout<<"OK"<<endl;
    } else {
      cout<<"NG"<<endl;
      }
  }
  else {
    cout<<"NG"<<endl;
  }

  }
  
  return 0;
}
void solve(void){
  
  int i,j;
  queue<P> que;
  memset(data,-1,sizeof(data));
  que.push(P(sy,sx));     //queにスタート位置の座標を格納
  data[sy][sx]=0;
  
  while(!que.empty()){    //queが空でない間
    P p=que.front();
    que.pop();
    
    if(p.first==gy && p.second==gx){
      goal=1;
      break;
    }
    for(i=0;i<4;i++){
      int ny=p.first+dy[i];
      int nx=p.second+dx[i];
      if(nx>=0 && nx<w && ny>=0 && ny<h && mass[ny][nx]==scolor && data[ny][nx]==-1){
	que.push(P(ny,nx));
	data[ny][nx]=1;
      }
    }
  }
  return;
}

C++: #include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;
bool solve(int x,int y,int c);
int ux[2][8]={{0,1,2,3,0,1,2,3},
	      {0,1,0,1,0,1,0,1}};
int uy[2][8]={{0,0,0,0,1,1,1,1},
	      {0,0,1,1,2,2,3,3}};
int dx[4]={0,1,0,-1};
int dy[4]={-1,0,1,0};
int w,h,n;
int b[105][105];
int xs,ys,xg,yg;
int main(void){
  while(1){
    scanf("%d %d",&w,&h);
    if(!w && !h) break;
    memset(b,0,sizeof(b));
    scanf("%d %d %d %d",&xs,&ys,&xg,&yg);
    scanf("%d",&n);
    int c,d,tx,ty;
    for(int i=0;i<n;i++){
      scanf("%d %d %d %d",&c,&d,&tx,&ty);
      for(int j=0;j<8;j++){
	b[tx+ux[d][j]][ty+uy[d][j]]=c;
      }
    }
    if(b[xs][ys]!=0 && b[xg][yg]!=0 && b[xs][ys]==b[xg][yg] && solve(xs,ys,b[xs][ys])) puts("OK");
    else puts("NG");
  }
}

bool solve(int x,int y,int c){
  if(x==xg && y==yg) return true;
  b[x][y]=0;
  for(int i=0;i<4;i++){
    int nx=x+dx[i];
    int ny=y+dy[i];
    if(0<nx && nx<=w && 0<ny && ny<=h){
      if(b[nx][ny]==c){
	if(solve(nx,ny,c)) return true;
      }
    }
  }
  return false;
}

C++: #include<bits/stdc++.h>
using namespace std;
#define ANSWER(x) cout<<x<<endl
#define debug(x) cout<<#x<<": "<<x
const int BA = 1000;
const int INFTY = (1<<21);
int xg,yg,w,h,gc;
int maps[101][101];
int solve(int ys,int xs);
int main(){
  int tate[2] = {2,4};
  int yoko[2] = {4,2};
  int xs,ys,n;
  int c[101],d[101],x[101],y[101];
  while(1){
    fill(maps[0],maps[101],0);
    cin >> w >> h;
    if(w==0 && h==0)break;
    cin >> xs >> ys >> xg >> yg >> n;
    for(int i=0;i<n;i++){
      cin >> c[i] >> d[i] >> x[i] >> y[i];
    }
    for(int i=0;i<n;i++){
      for(int j=y[i];j<y[i]+tate[d[i]];j++){
	for(int k=x[i];k<x[i]+yoko[d[i]];k++){
	  if(j == ys && k == xs)gc = c[i];
	  maps[j-1][k-1] = c[i];
	}
      }
    }
    /* for(int i=0;i<h;i++){
       for(int j=0;j<w;j++){
       cout << maps[i][j];
       }
       cout << endl;
       }*///マップ確認用
    if(solve(ys-1,xs-1))cout << "OK\n";
    else cout << "NG\n";
  }
}
int solve(int ys,int xs){
  if(xs < 0 || ys < 0 || xs > w-1 || ys > h-1 || maps[ys][xs] == 0 || maps[ys][xs] != gc){
    return 0;
  }
  else if(maps[ys][xs] == maps[yg-1][xg-1]){
    return 1;
  }
  maps[ys][xs] = 0;
  return solve(ys+1,xs) + solve(ys,xs+1)+ solve(ys-1,xs) + solve(ys,xs-1);
}