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 <bits/stdc++.h>
using namespace std;

int main() {
    int H, W;
    while (cin >> W >> H, H || W) {
        int sx, sy, gx, gy;
        cin >> sx >> sy >> gx >> gy;
        int M;
        cin >> M;
        vector<vector<int> > d(H, vector<int>(W));
        vector<vector<int> > used(H, vector<int>(W));

        for (int i = 0; i < M; i++) {
            int c, dir, x, y;
            cin >> c >> dir >> x >> y;
            if (dir) {
                for (int j = 0; j < 2; j++) {
                    for (int k = 0; k < 4; k++) {
                        d[x + j][y + k] = c;
                    }
                }
            } else {
                for (int j = 0; j < 4; j++) {
                    for (int k = 0; k < 2; k++) {
                        d[x + j][y + k] = c;
                    }
                }
            }
        }

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

        queue<int> qx, qy;
        qx.push(sx);
        qy.push(sy);

        while (qx.size()) {
            int x = qx.front(); qx.pop();
            int y = qy.front(); qy.pop();

            if (used[x][y]) continue;
            used[x][y] = 1;

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

                if (0 <= nx && nx < H && 0 <= ny && ny < W && !used[nx][ny] && d[x][y] == d[nx][ny]) {
                    qx.push(nx);
                    qy.push(ny);
                }
            }
        }

        if (used[gx][gy]) cout << "OK" << endl;
        else cout << "NG" << endl;
    }

    return 0;
}

C++: #include <iostream>
#include <cstdio>

using namespace std;

int field[102][102];
bool visited[102][102];
int w, h;
int xs, ys;
int xg, yg;
int n;
int d_x[] = {1, 0, -1, 0};
int d_y[] = {0, -1, 0, 1};
int sc;

bool search(int y, int x) {
  if (visited[y][x] || field[y][x] == 0 || field[y][x] != sc) {return false;}  
  if (y == yg && x == xg) {
    return true;
  }
  visited[y][x] = true;
  for (int i = 0; i < 4; i++) {
    if (search(y + d_y[i], x + d_x[i])) {return true;}
  }
  return false;
}

int main()
{
  while (true) {
    scanf("%d %d ", &w, &h);
    if (w == 0 && h == 0) {
      break;
    }
    scanf("%d %d ", &xs, &ys);
    scanf("%d %d ", &xg, &yg);
    scanf("%d ", &n);
    for (int i = 0; i < 102; i++) {
      fill(field[i], &field[i][102], 0);
      fill(visited[i], &visited[i][102], false);
    }
    for (int i = 0; i < n; i++) {
      int c, d, x, y;
      scanf("%d %d %d %d ", &c, &d, &x, &y);
      for (int i = 0; i < 2; i++) {
	for (int j = 0; j < 4; j++) {
	  if (d == 0) {
	    field[y + i][x + j] = c;
	  } else {
	    field[y + j][x + i] = c;
	  }
	}
      }
    }
    /*for (int i = 1; i <= h; i++) {
      for (int j = 1; j <= w; j++) {
	printf("%d ", field[i][j]);
      }
      printf("\n");
      }*/
    sc = field[ys][xs];
    if (search(ys, xs)) {cout << "OK" << endl;}
    else {cout << "NG" << endl;}
  }
  return 0;
}

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


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

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

typedef pair<short,short> P;
P S,G;
short w,h;

short color;
	queue<P> que;
	
bool check(short maze[MAX][MAX])
{
	que.push(S);

	color = maze[S.second][S.first];

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

		if(p == G){
			while(que.size())
				que.pop();
			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)
{
	short n,c,d,x,y;
	short maze[MAX][MAX];
	while(cin >> w >> h, w){
		rep(i,MAX){
			rep(j,MAX)
				maze[i][j] = -10;
		}
		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(maze[S.second][S.first] == -10 && maze[S.second][S.first] == maze[G.second][G.first] && check(maze))
			cout << "OK\n";
		else
			cout << "NG\n";

	}
	
	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<20;i++){
     for(int j=0;j<20;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;
if(c == 0){
cout << "NG"<<endl;
continue;
}
   meiro(xs,ys,C[xs][ys]);
   //print(w,h);

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

 return 0;
}