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<stdio.h>
int main(void)
{
	int w,h;
	int map[101][101];
	int st[2],go[2];
	int i,j,k;
	int num;
	int b_c,b_ang,b_x,b_y;
	int sign;
	int ans;
	
	for(;;)
	{
		ans=0;
		
		for(i=0;i<100;i++)
		{
			for(j=0;j<100;j++)
				map[i][j]=0;
		}
		
		scanf("%d%d",&w,&h);
		
		if(w==0 && h==0)
			break;
		
		scanf("%d%d%d%d",&st[0],&st[1],&go[0],&go[1]);
		
		
		scanf("%d",&num);
		
		for(i=0;i<num;i++)
		{
			scanf("%d%d%d%d",&b_c,&b_ang,&b_x,&b_y);
			
			if(b_ang==0)
			{
				for(j=0;j<4;j++)
				{
					for(k=0;k<2;k++)
						map[b_x+j][b_y+k]=b_c;
				}
			}
			else
			{
				for(j=0;j<4;j++)
				{
					for(k=0;k<2;k++)
						map[b_x+k][b_y+j]=b_c;
				}
			}
		}
		
		if(map[st[0]][st[1]]==0 || map[go[0]][go[1]]==0)
			printf("NG\n");
		else
		{
			sign=map[st[0]][st[1]];
			
			for(i=0;i<w;i++)
			{
				for(j=0;j<h;j++)
				{
					if(map[i][j]!=sign)
						map[i][j]=0;
				}
			}
			
			map[st[0]][st[1]]=-1;
			map[go[0]][go[1]]=-2;
			
			for(i=st[0],j=st[1];;)
			{
				if(map[i+1][j]==-2 || map[i][j+1]==-2 || map[i-1][j]==-2 || map[i][j-1]==-2)
				{
					ans=1;
					break;
				}
				else if(map[i-1][j]!=0 && map[i][j-1]!=0 && map[i+1][j]!=0 && map[i][j+1]!=0)
				{
					if(map[i+1][j]==sign)
					{
						map[i][j]=7;
						i++;
					}
					else if(map[i][j+1]==sign)
					{
						map[i][j]=7;
						j++;
					}
					else if(map[i-1][j]==sign)
					{
						map[i][j]=7;
						i--;
					}
					else if(map[i][j-1]==sign)
					{
						map[i][j]=7;
						j--;
					}
				}
				else if(map[i+1][j]!=sign && map[i][j+1]==sign)//ツ可コ
				{
					map[i][j]=7;
					j++;
				}
				else if(map[i+1][j]!=sign && map[i][j-1]==sign)//ツ湘」
				{
					map[i][j]=7;
					j--;
				}
				else if(map[i-1][j]!=sign && map[i][j+1]==sign)//ツ可コ
				{
					map[i][j]=7;
					j++;
				}
				else if(map[i-1][j]!=sign && map[i][j-1]==sign)//ツ湘」
				{
					map[i][j]=7;
					j--;
				}
				else if(map[i+1][j]==sign/* && map[i][j-1]!=sign*/)//ツ右
				{
					map[i][j]=7;
					i++;
				}
				else if(map[i-1][j]==sign/* && map[i][j+1]!=sign*/)//ツ債カ
				{
					map[i][j]=7;
					i--;
				}
				else if(map[i+1][j]!=sign && map[i][j+1]!=sign && map[i-1][j]!=sign && map[i][j-1]!=sign)
				{
					ans=2;
					break;
				}
			}
			if(ans==1)
				printf("OK\n");
			else if(ans==2)
				printf("NG\n");
		}
	}
}

C++: #include<iostream>

int field[101][101];//y,x
bool flag;
int n,a,sx,sy,gx,gy,col;

void erase(){
	for(int i=0; i<101; i++)
		for(int j=0; j<101; j++)
			field[i][j] = 0;
}

void DFS(int x, int y){
	int xx = x;
	int yy = y;

	if(xx == gx && yy == gy){
		flag = true;
		return;
	}

	xx++;
	if(field[yy][xx] == col)
		DFS(xx, yy);
	if(flag)
		return;

	if(xx > 1){
		xx--;
		yy++;
		if(field[yy][xx] == col)
			DFS(xx, yy);
	}
	if(flag)
		return;
	
	if(yy > 1 && xx > 1){	
		xx--;
		yy--;
		if(field[yy][xx] == col)
			DFS(xx, yy);
	}
	if(flag)
		return;
	
	if(yy > 1){		
		xx++;
		yy--;
		if(field[yy][xx] == col)
			DFS(xx, yy);
	}
}

int main(){
	int c,d,bx,by;
	using std::cin;
	while(true){
		flag = false;
		erase();
		cin >> n >> a;
		if(!n && !a)
			return 0;
		cin >> sx >> sy;
		cin >> gx >> gy;
		cin >> n;
		for(int i=0; i<n; i++){
			cin >> c >> d >> bx >> by;
			if(d==0){
				for(int h=by; h<by+2; h++)
					for(int k=bx; k<bx+4; k++)
						field[h][k] = c;
			}
			else{
				for(int h=by; h<by+4; h++)
					for(int k=bx; k<bx+2; k++)
						field[h][k] = c;
			}
		}
		col = field[gy][gx];
		DFS(sx, sy);
		if(flag)
			std::cout << "OK\n";
		else
			std::cout << "NG\n";
	}
}

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

int F[102][102] = { 0 };

void DFS(int Y, int X, int c) {
	//cout << Y << " " << X << endl;
	if (F[Y][X] != c)
		return;
	F[Y][X] = 10;
	DFS(Y - 1, X, c);//???
					 //DFS(Y - 1, X+1, A_ito);//??????
	DFS(Y, X + 1, c);//???
					 //DFS(Y + 1, X+1, A_ito);//??????
	DFS(Y + 1, X, c);//???
					 //DFS(Y + 1, X-1, A_ito);//??????
	DFS(Y, X - 1, c);//???
					 //DFS(Y - 1, X-1, A_ito);//??????
}


int main()
{
	int xs, ys, xg, yg, n;
	int c, d, x, y;
	int W = 1, H = 1;

	while ((W != 0) && (H != 0)) {
		cin >> W >> H;
		/*for (int i = 1;i <= H;i++) {
			for (int j = 1;j <= W;j++) {
				F[i][j] = 6;
			}
		}*/
		cin >> xs >> ys >> xg >> yg >> n;
		for (int i = 1;i <= n;i++) {
			cin >> c >> d >> x >> y;
			if (d == 0) {
				F[x][y] = c;
				F[x][y + 1] = c;
				F[x + 1][y] = c;
				F[x + 1][y + 1] = c;
				F[x + 2][y] = c;
				F[x + 2][y + 1] = c;
				F[x + 3][y] = c;
				F[x + 3][y + 1] = c;
			}
			if (d == 1) {
				F[x][y] = c;
				F[x + 1][y] = c;
				F[x][y + 1] = c;
				F[x + 1][y + 1] = c;
				F[x][y + 2] = c;
				F[x + 1][y + 2] = c;
				F[x][y + 3] = c;
				F[x + 1][y + 3] = c;
			}
		}
		
			DFS(ys, xs, F[ys][xs]);

		if (F[yg][xg] == 10) {
			cout << "OK" << endl;
		}
		else { cout << "NG" << endl; }
		/*for (int i = 0;i <= H;i++) {
			for (int j = 0;j <= W;j++) {
				F[i][j] = 0;
			}
		}
		*/
	}

	return 0;
}