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 <string.h>
#include <queue>
using namespace std;
struct q{
    int x,y,color,cnt;
};
queue <q> pipe;
q Main,sub;
int sy,sx;
int gy,gx;
int w,h,n;
int board[101][101];
int visited[101][101];
int state[4];

void put(int mode,int color,int x,int y);

int main(void){
    cin>>w>>h;
    while(w!=0&&h!=0){
        cin>>sx>>sy;
        cin>>gx>>gy;
        cin>>n;
        memset(board,0,sizeof(board));
        memset(visited,0,sizeof(visited));
        for(int i=0;i<n;i++){
            cin>>state[0]>>state[1]>>state[2]>>state[3];
            put(state[1],state[0],state[2],state[3]);
        }
        
        Main.x=sx;
        Main.y=sy;
        Main.cnt=0;
        Main.color=board[sx][sy];
        visited[sx][sy]=1;
        pipe.push(Main);
        
        int mx,fx[]={0,1,0,-1};
        int my,fy[]={1,0,-1,0};
        
        while(!pipe.empty()){
            Main=pipe.front();
            pipe.pop();
            for(int i=0;i<4;i++){
                mx=Main.x+fx[i];
                my=Main.y+fy[i];
                if(mx>=1&&mx<=100&&my>=1&&my<=100&&Main.color==board[mx][my]&&visited[mx][my]==0){
                    sub=Main; visited[mx][my]=1;
                    sub.x=mx; sub.y=my; sub.cnt++;
                    pipe.push(sub);
                }
            }
        }
        if(visited[gx][gy]==1){cout<<"OK"<<endl;}
        else{cout<<"NG"<<endl;}
        cin>>w>>h;
    }
}

void put(int mode,int color,int x,int y){
    int X[2],Y[2];
    X[0]=4; Y[0]=2;
    X[1]=2; Y[1]=4;
    for(int i=x;i<x+X[mode];i++){
        for(int j=y;j<y+Y[mode];j++){
            board[i][j]=color;
        }
    }
}

C++: #include <iostream>
#include<queue>
#include<string.h>
using namespace std;
#define TATE 1
#define YOKO 0

struct ST {
        int x;
        int y;
    };

int main(void){
    int map[101][101];
    int board[101][101];
    int T[]={0,-1,1,0};
    int Y[]={1,0,0,-1};
    int w,h,xs,xg,ys,yg,n,color,muki,x,y;
    
    ST RE;
    ST GO;
    queue <ST> Q;
    while(1){
        memset(map,0,sizeof(map));
        memset(board,0,sizeof(board));
        cin>>w>>h;
        if(w==0&&h==0)break;
        cin>>xs>>ys>>xg>>yg>>n;
        for(int i=0;i<n;i++){
            cin>>color>>muki>>x>>y;
            if(muki==YOKO){
                for(int j=0;j<4;j++){
                    board[y][x+j]=board[y+1][x+j]=color;
                }
            }
            else{
                for(int j=0;j<4;j++){
                    board[y+j][x]=board[y+j][x+1]=color;
                }
            }
        }
       /* for(int i=1;i<=h;i++){
            for(int j=1;j<=w;j++){
                cout<<board[i][j];
            }
            cout<<endl;
        }*/
        RE.x=xs;
        RE.y=ys;
        map[ys][xs]=1;
        Q.push(RE);
        int flag=0;
        while(!Q.empty()){
            RE=Q.front();
            Q.pop();
            if(RE.x==xg&&RE.y==yg&&board[RE.y][RE.x]==board[yg][xg]){
                flag=1;
                //cout<<RE.x<<" "<<RE.y<<endl;
                break;
            }
            else{
                for(int i=0;i<4;i++){
                    GO=RE;
                    if(GO.x+Y[i]>0&&GO.y+T[i]>0&&GO.x+Y[i]<101&&GO.y+T[i]<101&&board[GO.y+T[i]][GO.x+Y[i]]==board[GO.y][GO.x]&&map[GO.y+T[i]][GO.x+Y[i]]!=1){
                        GO.x+=Y[i];
                        GO.y+=T[i];
                        map[GO.y][GO.x]=1;
                        Q.push(GO);
                    }
                }
            }
        }
       /* for(int i=0;i<h;i++){
            for(int j=0;j<w;j++){
                cout<<board[i][j];
            }
            cout<<endl;
        }*/
        if(flag==1){
            cout<<"OK"<<endl;
        }
        else{
            cout<<"NG"<<endl;
        }
    }
    
}

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

int F[102][102];
int xg,yg;
int flag = 0;

void DFS(int Y,int X,int c){
  if(F[Y][X]!=c){
    return;
  }
  if(Y == xg && X == yg){
    flag = 1;
  }

  F[Y][X] = 0;
  DFS(Y-1,X  ,c);
  //DFS(Y-1,X+1,c);
  DFS(Y  ,X+1,c);
  //DFS(Y+1,X+1,c);
  DFS(Y+1,X  ,c);
  //DFS(Y+1,X-1,c);
  DFS(Y  ,X-1,c);
  //DFS(Y-1,X-1,c);
}


int main(){
  int w,h,xs,ys,n;
  while(1){
  cin >> w >> h >> xs >> ys >> xg >> yg >> n;
  if(w == 0 && h == 0)
    break;
  for(int i=0;i<n;i++){
    int c,d,x,y;
    cin >> c >> d >> x >> y;
    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(flag == 1){
    cout << "OK" << endl;
  } else {
    cout << "NG" <<endl;
  }
}
}

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

int w,h,sx,sy,gx,gy,n;
int f[128][128];

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

bool dfs(int x, int y)
{
	if(f[y][x]==0)
	{
		return false;
	}
	if(x==gx && y==gy)
	{
		return true;
	}

	int c = f[y][x];
	f[y][x] = 0;
	for(int i=0; i<4; i++)
	{
		int nx = x+dx[i];
		int ny = y+dy[i];

		if(f[ny][nx]==c)
		{
			if(dfs(nx,ny))
			{
				return true;
			}
		}
	}

	return false;
}

int main()
{
	while(cin >> w >> h, w||h)
	{
		for(int y=0; y<128; y++)
		for(int x=0; x<128; x++)
		{
			f[y][x] = 0;
		}

		cin >> sx >> sy >> gx >> gy >> n;
		for(int i=0; i<n; i++)
		{
			int c,d,xx,yy,px,py;
			cin >> c >> d >> xx >> yy;

			px = (1-d)*2;
			py = (  d)*2;

			for(int y=0; y<2; y++)
			for(int x=0; x<2; x++)
			{
				f[yy   +y][xx   +x] = c;
				f[yy+py+y][xx+px+x] = c;
			}
		}
		
		cout << (dfs(sx,sy)?"OK":"NG") << endl;
	}
	return 0;
}