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<stack>
#include<queue>
#include<cstdio>
using namespace std;

#define X_MAX 100+10
#define Y_MAX 100+10

#define Vertical 1
#define Horizontal 0

int my[4] = { 1,-1,0,0 };
int mx[4] = { 0,0,1,-1 };

struct ST
{
	int came[Y_MAX][X_MAX];
	int now_y;
	int now_x;
};


void paint_V(int*map , int col)
{
	int i;
	for (i = 0; i < 2; i++)
	{
		*(map + i) = col;
	}
}

void paint_H(int*map, int col)
{
	int i;
	for (i = 0; i < 4; i++)
	{
		*(map + i) = col;
	}
}


void chek(int map[Y_MAX][X_MAX],int lx,int ly)
{
	int i, j;
	for (i = 0; i <= ly+1;i++)
	{
		for (j = 0; j <= lx+1; j++)
		{
			cout << map[i][j];
		}
		cout << endl;
	}
}


int main(void)
{
	ST an = {0}, tmp;
	queue<ST> ma;

	int lx, ly, n;
	int sx, sy, gx, gy;
	int col, VorH,set_x,set_y;
	int i, j;

	while ((cin >> lx >> ly), lx!=0&&ly!=0)
	{
		int goal = 0;
		int map[Y_MAX][X_MAX] = { 0 };
		cin >> sx >> sy >> gx >> gy >> n;

		for (i = 0; i < n; i++)
		{
			cin >> col >> VorH >> set_x >> set_y;
			if (VorH == Vertical)
			{
				for (j = 0; j < 4; j++)
				{
					paint_V(map[set_y + j] + set_x, col);
				}
			}
			else
			{
				for (j = 0; j < 2; j++)
				{
					paint_H(map[set_y + j] + set_x, col);
				}
			}
		}
		
		int s_col = map[sy][sx];
		if (s_col == 0)
		{
			cout << "NG\n";
			continue;
		}

		an.now_y = sy;
		an.now_x = sx;
		ma.push(an);

		//chek(map, lx, ly);

		while (!ma.empty())
		{
			an = ma.front();
			ma.pop();
			an.came[an.now_y][an.now_x] = 1;

			//printf("y=%d,x=%d\n", an.now_y, an.now_x);
			//chek(an.came, lx, ly);

			if (an.now_y == gy && an.now_x == gx)
			{
				goal = 1;
				break;
			}

			tmp = an;

			for (i = 0; i < 4; i++)
			{
				if (map[an.now_y + my[i]][an.now_x + mx[i]] == s_col && an.came[an.now_y + my[i]][an.now_x + mx[i]] == 0)
				{
					tmp.now_y = an.now_y + my[i];
					tmp.now_x = an.now_x + mx[i];
					ma.push(tmp);
				}
			}

		}
		if (goal == 1)
		{
			while (!ma.empty())
			{
				ma.pop();
			}
			cout << "OK\n";
		}
		else
		{
			cout << "NG\n";
		}


	}
	return 0;
}

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

char F[102][102];
int xg,yg;

int DFS(int Y,int X,char c){
  if(F[Y][X]!=c){
    return 0;
  }
  if(Y == xg && X == yg){
    return 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;
  cin >> w >> h >> xs >> ys >> xg >> yg >> n;
  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;
      }
    }
  }

  if(DFS(xs,ys,F[xs][ys]) == 1){
    cout << "OK" << endl;
  } else {
    cout << "NG" << endl;
  }

}

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

int map[102][102];

void route(int w, int h, int color) {
	if (map[w][h] != color)
		return;
	map[w][h] = 10;
	route(w, h + 1, color);
	route(w + 1, h, color);
	route(w, h - 1, color);
	route(w - 1, h, color);
}


int main() {
	int h, w, xs, ys, xg, yg, n;
	int c, d, x, y,color;

	while (1) {
		cin >> w >> h;		
		if (w == 0 && h == 0)
			break;

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

		for (int i = 0; i<n; i++) {
			cin >> c >> d >> x >> y;
			if (d == 0) {
				for (int j = 0; j < 4; j++)
					map[j + x][y] = map[j + x][y + 1] = c;
			}
			else {
				for (int j = 0; j < 4; j++)
					map[x][y + j] = map[x + 1][y + j] = c;
			}
		}

		color = map[xs][ys];
		route(xs, ys, color);

		
		if (map[xg][yg]==10)
			cout << "OK" << endl;
		else
			cout << "NG"<<endl;
	}

	return 0;
}