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 a[102][102],color;

void dfs(int x,int y){
  
  if(x < 102 && y < 102){
  
    a[y][x] = 9;
    
    if(a[y+1][x] == color){
      dfs(x,y+1);
    }
    if(a[y][x+1] == color){
      dfs(x+1,y);
    }
    if(a[y-1][x] == color){
      dfs(x,y-1);
    } 
    if(a[y][x-1] == color){
      dfs(x-1,y);
    }
  
  }

} 

int main(){

  int xs,ys,xg,yg,n,c,d,x,y,w,h;

  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++){
	a[i][j]=0;
      }
    }

    cin >>xs>>ys;
    cin >>xg>>yg;

    cin >>n;

    for(int i = 0 ; i < n ; i++){
      
      cin >> c >> d >> x >> y;
      
      if( d == 0 ){
	for(int i = 0 ; i < 2 ; i++){
	  for(int j = 0 ; j < 4 ; j++){
	    a[i+y][j+x] = c;
	  }
	}
      }else{
	for(int i = 0 ; i < 4 ; i++){
	  for(int j = 0 ; j < 2 ; j++){
	    a[i+y][j+x] = c;
	  }
	}
      }
    
    }
    
    /*
      for(int i = 0 ; i < h+2 ; i ++){
      for(int j = 0 ; j < w+2 ; j++){
      cout << a[i][j];
      }
      cout <<endl;
      }
      cout <<endl;
    */
    
    color = a[ys][xs];
    dfs(xs,ys);
    
    /*
      for(int i = 0 ; i < h+2 ; i ++){
      for(int j = 0 ; j < w+2 ; j++){
      cout << a[i][j];
      }
      cout <<endl;
      }
    */
    
    if(a[yg][xg] == 9){
      cout <<"OK"<<endl;
    }else{
      cout <<"NG"<<endl;
    }
    
  }      
  
  return 0;
  
}

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

int Board[102][102];    //Board[j, x, w][i, y, h]
bool isOK;              //迷路がOKかNGか
int xs, ys, xg, yg;     //StartとGoalの座標

void DFS(int c, int x, int y){
    if(Board[x][y] != c){
        return;
    }
    else if(x==xg && y==yg){
        isOK = true;    //Goalなら迷路はOK
        return;
    }

    Board[x][y] = 0;

    DFS(c, x+1, y  );
    DFS(c, x  , y+1);
    DFS(c, x-1, y  );
    DFS(c, x  , y-1);
}

int main(){
    int w,h;
    while(true){
        cin >> w >> h;
        if(w==0 && h==0)
            break;
        
        isOK = false;               //初期値をNGに
        for(int i=1;i<=100;i++){    //Boardの初期化
            for(int j=1;j<=100;j++)
                Board[j][i] = -1;
        } 
        cin >> xs >> ys >> xg >> yg;

        int n, c, d, x, y;
        cin >> n;
        for(int t=0;t<n;t++){
            cin >> c >> d >> x >> y;
            int wb = 2+(!d*2);      //d=0なら横長
            int hb = 2+(d*2);       //d=1なら縦長
            for(int i=0;i<hb;i++){
                for(int j=0;j<wb;j++)
                    Board[x+j][y+i] = c;
            }
        }

        DFS(Board[xs][ys], xs, ys);

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

    return 0;
}

C++: #include <iostream>
#include <stdio.h>
#include <queue>
using namespace std;
class node{
public:
	int x,y;
	void set(int xx,int yy){
		x = xx;
		y = yy;
	}
	bool check(int w,int h){
		if(x>=0&&y>=0){
			if(x<=w&&y<=h) return true;
		}
		return false;
	}
	
};

int main(){
	int w,h;
	while(1){
		//printf("w:%d,h:%d\n",w,h);
		int xs,ys,xg,yg,n,c,dir,x,y;
		int i,j;
		int color[101][101];
		int dx[4]={-1,0,1,0},dy[4]={0,-1,0,1};
		bool visited[101][101];
		queue<node> q;
		node a;
		scanf("%d%d",&w,&h);
		if(w==0&&h==0) break;
		scanf("%d%d",&xs,&ys);
		scanf("%d%d",&xg,&yg);
		scanf("%d",&n);
	
		while(n--){
			scanf("%d%d%d%d",&c,&dir,&x,&y);
			if(dir==0){
				for(i=0;i<2;i++){
					for(j=0;j<4;j++) color[x+j][y+i] = c;
				}
			}
			else{
				for(i=0;i<2;i++){
					for(j=0;j<4;j++) color[x+i][y+j] = c;
				}
			}
		}
		a.set(xs,ys);
		q.push(a);
		visited[a.x][a.y]=true;
		while(!q.empty()){
			a = q.front();
			q.pop();
			for(int i=0;i<4;i++){
				a.x += dx[i];
				a.y += dy[i];
				if(!a.check(w,h)&&(color[xs][ys]==color[a.x][a.y])&&!visited[a.x][a.y]){
					q.push(a);
					if(a.x==xg&&a.y==yg) break;
					visited[a.x][a.y] = true;
				}
			}
		}
		if(visited[xg][yg]) printf("OK\n");
		else printf("NG\n");
	}

	return 0;
}