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>
using namespace std;

int F[102][102];

bool DFS(int X, int Y, int Xg, int Yg, int c){
	if(F[Y][X] != c){
		return false;
	}else if(F[Y][X] == c && X == Xg && Y == Yg){
		return true;
	}
	F[Y][X] = -1;
	if(DFS(X, Y - 1, Xg, Yg, c)){
		return true;
	}else if(DFS(X + 1, Y, Xg, Yg, c)){
		return true;
	}else if(DFS(X, Y + 1, Xg, Yg, c)){
		return true;
	}else if(DFS(X - 1, Y, Xg, Yg, c)){
		return true;
	}
	
	return false;
}

int main(){

while(true){
	int w, h;
	cin >> w >> h;
	if(w == 0 && h == 0){
		break;
	}
	int xs, ys, xg, yg;
	cin >> xs >> ys >> xg >> yg;
	int n;
	cin >> n;
	
	for(int i = 0; i < n; i++){
		int c, d, x, y;
		cin >> c >> d >> x >> y;
		if(d == 0){
			for(int X = x; X < x + 4; X++){
				for(int Y = y; Y < y + 2; Y++){
					F[Y][X] = c;
				}
			}
		}else if(d == 1){
			for(int X = x; X < x + 2; X++){
				for(int Y = y; Y < y + 4; Y++){
					F[Y][X] = c;
				}
			}
		}
	}
	if(DFS(xs, ys, xg, yg, F[xg][yg])){
		cout << "OK" << endl;
	}else{
		cout << "NG" << endl;
	}
}
	return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
int w,h;
int gx,gy;
int iro;
int mas[101][101];
int dy[4]={0,1,-1,0};
int dx[4]={1,0,0,-1};
int flag;
void solve(int x,int y){
  if(iro==0) return;
  if(x==gx-1 && y==gy-1){
    flag=1;
    return;
  }
  for(int i=0;i<4;i++){
    int ny=y+dy[i];
    int nx=x+dx[i];
    if(0<=ny && 0<=nx && ny<h && nx<w && mas[ny][nx]==iro){
      mas[ny][nx]=0;
      solve(nx,ny);
    }
  }
  return;
}
int main(){
  int n;
  int sx,sy;
  while(1){
    cin>>w>>h;
    if(w==0 && h==0) break;
    for(int i=0;i<h;i++){
      for(int j=0;j<w;j++){
	mas[i][j]=0;
      }
    }
    cin>>sx>>sy;
    cin>>gx>>gy;
    cin>>n;
    for(int i=0;i<n;i++){
      int c,d,x,y;
      cin>>c>>d>>x>>y;
      if(d==0){
	for(int i=0;i<2;i++){
	  for(int j=0;j<4;j++){
	    mas[y-1+i][x-1+j]=c;
	  }
	}
      }else{
	for(int i=0;i<4;i++){
	  for(int j=0;j<2;j++){
	    mas[y-1+i][x-1+j]=c;
	  }
	}
      }
    }
    //for(int i=0;i<h;i++){
    //for(int j=0;j<w;j++){
    //	cout<<mas[i][j];
    //}
    //cout<<endl;
    //}

    iro=mas[sy-1][sx-1];
    //cout<<iro<<endl;
    flag=0;
    solve(sx-1,sy-1);
    if(flag){
      cout<<"OK"<<endl;
    }else{
      cout<<"NG"<<endl;
    }
  }
}

C++: #include<iostream>
#include<algorithm>
using namespace std;
int a[100][100],b[100][100];
bool o[100][100];
bool l;
void solve(int w,int h,int xg, int yg,int c,int n,int m) {
	if (m<h-1&&a[n][m+1] == c) {
		b[n][m + 1] = min(b[n][m] + 1, b[n][m + 1]);
		if (n == xg&&m + 1 == yg) {
			l = true; return;
		}
		a[n][m + 1] = 0;
		solve(w,h,xg, yg, c, n, m + 1);
	}
	if (m > 0 && a[n][m - 1] == c) {
		b[n][m - 1] = min(b[n][m] + 1, b[n][m - 1]);
		if (n == xg&&m - 1 == yg) {
			l = true;
			return;
		}
		a[n][m - 1] = 0;
		solve(w, h, xg, yg, c, n, m - 1);
	}
	if (n<w - 1 && a[n+1][m ] == c) {
		b[n+1][m] = min(b[n][m] + 1, b[n+1][m]);
		if (n + 1 == xg&&m == yg) { l = true; return; }
		a[n + 1][m] = 0;
		solve(w, h, xg, yg, c, n+1,m);
	}
	if (n>0 && a[n-1][m] == c) {
		b[n-1][m] = min(b[n][m] + 1, b[n-1][m]);
		if (n == xg&&m == yg) { l = true; return; }
		a[n - 1][m] = 0;
		solve(w, h, xg, yg, c, n-1, m);
	}
}
int main() {
	int w, h;
	while (cin >> w >> h&&w != 0 && h != 0) {
		int xs, ys, xg, yg,n;
		cin >> xs >> ys;
		cin >> xg >> yg;
		cin >> n;
		for (int i = 0; i < w; i++) {
			for (int j = 0; j < h; j++) {
				a[i][j] = 0;
				b[i][j] = 10000;
				o[i][j] = false;
			}
		}
		for (int i = 0; i < n; i++) {
			int c, d, x, y;
			cin >> c >> d >> y >> x;
			if (d == 0) {
				for (int z = 0; z < 2; z++) {
					for (int j = 0; j < 4; j++) 
						a[x + z-1][y + j-1] = c;
				}
			}
			else {
				for (int j = 0; j < 4; j++) {
					for (int z = 0; z < 2; z++) 
						a[x + j-1][y + z-1] = c;
				}
			}
		}
		int k = a[xs-1][ys-1];
		a[xs-1][ys-1] = 0;
		l=false;
		if(k!=0)
			solve(w,h,xg-1, yg-1, k,xs-1,ys-1);
		if (l) cout << "OK" << endl;
		else cout << "NG" << endl;
	}
}

C++: #include <cmath>
#include <ctime>
#include <algorithm>
#include <iostream>
#include <map>
#include <numeric>
#include <set>
#include <sstream>
#include <string>
#include <vector>
#include <list>
#include <deque>
#include <stack>
#include <bitset>
#include <functional>
#include <numeric>
#include <utility>
#include <iomanip>
#include <cstdio>
#include <cctype>
#include <queue>
#include <complex>
#include <climits>

typedef long long ll;

using namespace std;

int maze[110][110];
int f[110][110];
int w, h, xs, ys, xg, yg, res = 0;
int color;

void dfs(int cx, int cy){
	if(f[cx][cy]) return ;
	f[cx][cy] = 1;

	if(cx == xg && cy == yg){
		res = 1;
		return ;
	}
	for(int dx=-1; dx<=1; ++dx){
		for(int dy=-1; dy<=1; ++dy){
			if(abs(dx-dy) != 1) continue;
			int nx = cx + dx, ny = cy + dy;
			if(maze[nx][ny] == color){
				dfs(nx, ny);
			}
		}
	}
	return ;
}


int main(void){
	int n;
	while(cin >> w >> h){
		if(w == 0 && h == 0) break;
		cin >> xs >> ys >> xg >> yg >> n;
		for(int i=0; i<110; ++i){
			for(int j=0; j<110; ++j){
				maze[i][j] = 0;
				f[i][j] = 0;
			}
		}

		for(int i=0; i<n; ++i){
			int c, d, x, y;
			cin >> c >> d >> x >> y;
			if(d == 0){
				for(int j=y; j<=y+1; ++j){
					for(int k=x; k<=x+3; ++k){
						maze[j][k] = c;
					}
				}
			}
			if(d == 1){
				for(int j=y; j<=y+3; ++j){
					for(int k=x; k<=x+1; ++k){
						maze[j][k] = c;
					}
				}
			}
		}

		color = maze[xs][ys];

		dfs(xs, ys);

		if(res){
			cout << "OK" << endl;
		} else {
			cout << "NG" << endl;
		}
	}

	return 0;
}