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 MAX_N 1000
int x[MAX_N][MAX_N], y[MAX_N][MAX_N];
int H, W, N, X, Y, C, D, SX, SY, GX, GY;
int main() {
	while (true) {
		cin >> W >> H;
		if (H == 0 && W == 0) { break; }
		cin >> SX >> SY >> GX >> GY >> N;
		for (int i = 0; i < MAX_N; i++) {
			for (int j = 0; j < MAX_N; j++) {
				x[i][j] = 0; y[i][j] = 0;
			}
		}
		for (int i = 0; i < N; i++) {
			cin >> C >> D >> X >> Y;
			if (D == 0) {
				for (int j = Y; j < Y + 2; j++) {
					for (int k = X; k < X + 4; k++) {
						x[j][k] = C;
					}
				}
			}
			if (D == 1) {
				for (int j = Y; j < Y + 4; j++) {
					for (int k = X; k < X + 2; k++) {
						x[j][k] = C;
					}
				}
			}
		}
		queue<pair<int, int>>Q; Q.push(make_pair(SY, SX)); y[SY][SX] = 1;
		while (!Q.empty()) {
			pair<int, int>pa = Q.front(); Q.pop();
			int a1 = pa.first; int a2 = pa.second;
			if (y[a1 - 1][a2] == 0 && a1 - 1 >= 1 && x[a1][a2] == x[a1 - 1][a2]) { y[a1 - 1][a2] = 1; Q.push(make_pair(a1 - 1, a2)); }
			if (y[a1 + 1][a2] == 0 && a1 + 1 <= H && x[a1][a2] == x[a1 + 1][a2]) { y[a1 + 1][a2] = 1; Q.push(make_pair(a1 + 1, a2)); }
			if (y[a1][a2 - 1] == 0 && a2 - 1 >= 1 && x[a1][a2] == x[a1][a2 - 1]) { y[a1][a2 - 1] = 1; Q.push(make_pair(a1, a2 - 1)); }
			if (y[a1][a2 + 1] == 0 && a2 + 1 <= W && x[a1][a2] == x[a1][a2 + 1]) { y[a1][a2 + 1] = 1; Q.push(make_pair(a1, a2 + 1)); }
		}
		if (y[GY][GX] == 1) { cout << "OK" << endl; }
		if (y[GY][GX] == 0) { cout << "NG" << endl; }
	}
	return 0;
}

C++: #include<iostream>
#include<queue>
using namespace std;
int m[100][100],used[100][100];
int d[]={0,1,0,-1,0};
main()
{
	int w,h;
	while(cin>>w>>h,h)
	{
		for(int i=0;i<h;i++)for(int j=0;j<w;j++)used[i][j]=m[i][j]=0;
		int sx,sy,gx,gy;cin>>sy>>sx>>gy>>gx;
		sx--,sy--,gx--,gy--;
		int n;cin>>n;
		for(int i=0;i<n;i++)
		{
			int c,d,x,y;cin>>c>>d>>y>>x;
			x--,y--;
			if(d==0)
			{
				for(int j=0;j<2;j++)for(int k=0;k<4;k++)m[x+j][y+k]=c;
			}
			else
			{
				for(int j=0;j<4;j++)for(int k=0;k<2;k++)m[x+j][y+k]=c;
			}
		}
		if(m[sx][sy]==0)
		{
			cout<<"NG"<<endl;
			continue;
		}
		queue<pair<int,int> >P;
		P.push(make_pair(sx,sy));
		used[sx][sy]=1;
		while(!P.empty())
		{
			int x=P.front().first,y=P.front().second;
			P.pop();
			for(int r=0;r<4;r++)
			{
				int tx=x+d[r],ty=y+d[r+1];
				if(tx<0||ty<0||tx>=h||ty>=w||used[tx][ty]||m[tx][ty]!=m[sx][sy])continue;
				used[tx][ty]=1;
				P.push(make_pair(tx,ty));
			}
		}
		cout<<(used[gx][gy]?"OK":"NG")<<endl;
	}
}

C++: #include<stdio.h>
//#include<windows.h>
int main(void)
{
	int w,h;
	int map[101][101];
	int st[2],go[2];
	int i,j,k,l,m;
	int num;
	int b_c,b_ang,b_x,b_y;
	int sign;
	int ans;
	int maps=0;
	
	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");
		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;
					else
						maps++;
				}
			}
			
			map[st[0]][st[1]]=-1;
			map[go[0]][go[1]]=-2;
			
			for(i=st[0],j=st[1];;)
			{
				
/*
				for(m=0;m<h;m++)
				{
					for(l=0;l<w;l++)
					{
						printf("%d ",map[l][m]);
					}
					printf("%dツ行\n",l);
				}
				getchar();
				system("cls");
*/
				
				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++;
						maps--;
					}
					else if(map[i][j+1]==sign)
					{
						map[i][j]=7;
						j++;
						maps--;
					}
					else if(map[i-1][j]==sign)
					{
						map[i][j]=7;
						i--;
						maps--;
					}
					else if(map[i][j-1]==sign)
					{
						map[i][j]=7;
						j--;
						maps--;
					}
				}
				else if(map[i+1][j]==sign/* && map[i][j-1]!=sign*/)//ツ右
				{
//					printf("migi\n");
					map[i][j]=7;
					i++;
					maps--;
				}
				else if(/*map[i+1][j]!=sign && */map[i][j+1]==sign)//ツ可コ
				{
//					printf("sita1\n");
					map[i][j]=7;
					j++;
					maps--;
				}
				else if(map[i-1][j]==sign/* && map[i][j+1]!=sign*/)//ツ債カ
				{
//					printf("hidari\n");
					map[i][j]=7;
					i--;
					maps--;
				}
				else if(/*map[i+1][j]!=sign && */map[i][j-1]==sign)//ツ湘」
				{
//					printf("ue1\n");
					map[i][j]=7;
					j--;
					maps--;
				}
				else if(/*map[i-1][j]!=sign && */map[i][j+1]==sign)//ツ可コ
				{
//					printf("sita2\n");
					map[i][j]=7;
					j++;
					maps--;
				}
				else if(map[i-1][j]!=sign && map[i][j-1]==sign)//ツ湘」
				{
//					printf("ue2\n");
					map[i][j]=7;
					maps--;
					j--;
				}
				else if(map[i+1][j]!=sign && map[i][j+1]!=sign && map[i-1][j]!=sign && map[i][j-1]!=sign && maps==0)
				{
					ans=2;
					break;
				}
				else
				{
					
					map[i][j]=7;
					
					for(m=0;m<h;m++)
					{
						for(l=0;l<w;l++)
						{
							if((map[m][l]==sign && map[m][l+1]==7) || (map[m][l]==sign && map[m-1][l]))
							{
								i=m;
								j=l;
							}
						}
					}
				}
			}
			if(ans==1)
				printf("OK");
			else if(ans==2)
				printf("NG");
		}
	}
}
/*
20 20 
1 1
2 7
7
2 0 1 1
5 1 1 3
2 1 3 3
1 1 5 2
5 1 7 3
2 0 2 7
2 0 6 8
*/