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 <queue>
using namespace std;


#define rep(i,n) for(int i = 0; i < n; i++)
#define MAX 50

int dx[] = {0,0,-1,1},
	dy[] = {1,-1,0,0};

typedef pair<int,int> P;
P S,G;
int w,h;
int maze[MAX][MAX];
int color;

bool check()
{
	queue<P> que;
	que.push(S);
	color = maze[S.second][S.first];

	int nx,ny;
	while(que.size()){
		P p = que.front();	que.pop();

		if(p == G)
			return true;

		rep(i,4){
			nx = p.first + dx[i], ny = p.second + dy[i];
			
			if(nx > -1 && ny > -1 && nx < w && ny < h &&
				maze[ny][nx] == color){
					maze[ny][nx] = -1;
					que.push(P(nx,ny));
			}

		}
	}


	
	return false;
}

int main(void)
{
	int n,c,d,x,y;

	while(cin >> w >> h, w){
		cin >> S.first >> S.second;
		cin >> G.first >> G.second;
		S.first = S.first / 2;
		S.second= S.second/ 2;

		cin >> n;

		rep(i,n){
			cin >> c >> d >> x >> y;
			x /= 2;
			y /= 2;
			x++;
			y++;

			if(d == 0)
				maze[y][x] = maze[y][x+1] = c;
			else
				maze[y][x] = maze[y+1][x] = c;
		}
		
		if(check())
			printf("OK\n");
		else
			printf("NG\n");
/*
		rep(i,y){
			rep(j,x)
				printf("%2d", maze[i][j]);
			cout << endl;
		}

*/
	}
	
	return 0;
}

C++: #include<iostream>
#include<algorithm>
#include<cstring>

using namespace std;

typedef pair<int,int> P;
const int MAX = 101;

int maze[MAX][MAX];
bool come[MAX][MAX];
P s,g;
int W,H,c;
int dx[4] = {1,0,0,-1};
int dy[4] = {0,1,-1,0};

void init(){
  memset(come,false,sizeof(come));
  memset(maze,0,sizeof(maze));
}


void input_B(){
  int n;
  cin >> n;
  while(n--){
    int c,d,x,y;
    cin >> c >> d >> x >> y;
    if(d){
      for(int i = y; i < y+4; i++)
	for(int j = x; j < x+2; j++)
	  maze[i][j] = c;
    }else{
      for(int i = y; i < y+2; i++)
	for(int j = x; j < x+4; j++)
	  maze[i][j] = c;
    }
  }
}


void solve(P p){
  
  if(come[p.second][p.first] == false){
    come[p.second][p.first] = true;
    for(int i = 0; i < 4; i++)
      if(0 < p.first+dx[i] && p.first+dx[i] <= W &&
	 0 < p.second+dy[i] && p.second+dy[i] <= H &&
	 maze[p.second][p.first] == c) solve(P(p.first+dx[i],p.second+dy[i]));
  }
}

int main(){
  while(cin >> W >> H && W+H){
    init();
    cin >> s.first >> s.second;
    cin >> g.first >> g.second;
    input_B();
    c = maze[s.second][s.first];
    solve(s);
    if(come[g.second][g.first]) cout << "OK" << endl;
    else cout << "NG" << endl;
  }
  return 0;
}

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

bool b;
int dx[4]={1,0,-1,0};
int dy[4]={0,1,0,-1};
int board[105][105];

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 || board[tx][ty]!=c || board[tx][ty]==0 || 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;

int C[102][102];

void meiro(int W,int H,int c){
 if(C[W][H]!=c){
   return;
 }

 C[W][H] = -1;

 meiro(W-1,H  ,c);
 meiro(W  ,H+1,c);
 meiro(W+1,H  ,c);
 meiro(W  ,H-1,c);
}

void print(int w,int h){
   for(int i=1;i<=w;i++){
       for(int j=1;j<=h;j++){
           cout<<C[i][j]<<' ';
       }
       cout<<endl;
   }
}

int main(){
 while(1){
   int w,h;
   cin >> w >> h;
   if(w==0 && h==0){
     break;
   }

   for(int i=0;i<w;i++){
     for(int j=0;j<h;j++){
       C[i][j] = 0;
     }
   }

   int xs,ys,xg,yg;
   cin >> xs >> ys >> xg >> yg;

   int n;
   cin >> n;

   int c,d,x,y;
   for(int i=0;i<n;i++){
     cin >> c >> d >> x >> y;

     if(d==0){
       for(int j=x;j<x+4;j++){
         for(int k=y;k<y+2;k++){
           C[j][k]=c;
         }
       }
     }else{
       for(int j=x;j<x+2;j++){
         for(int k=y;k<y+4;k++){
           C[j][k]=c;
         }
       }
     }
   }
   //print(w,h);
   //cout << endl;
   meiro(xs,ys,C[xs][ys]);
   //print(w,h);

   if(C[xg][yg] == -1){
     cout << "OK" << endl;
   }else{
     cout << "NG" << endl;
   }
 }

 return 0;
}