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;
#define ANSWER(x) cout<<x<<endl
#define debug(x) cout<<#x<<": "<<x
const int BA = 1000;
const int INFTY = (1<<21);
int xg,yg,w,h;
int maps[101][101];
int solve(int xs,int ys);
int main(){
  int tate[2] = {2,4};
  int yoko[2] = {4,2};
  int xs,ys,n;
  int c[101],d[101],x[101],y[101];
  while(1){
    fill(maps[0],maps[101],0);
    cin >> w >> h;
    if(w==0 && h==0)break;
    cin >> xs >> ys >> xg >> yg >> n;
    for(int i=0;i<n;i++){
      cin >> c[i] >> d[i] >> x[i] >> y[i];
    }
    for(int i=0;i<n;i++){
      for(int j=y[i];j<y[i]+tate[d[i]];j++){
	for(int k=x[i];k<x[i]+yoko[d[i]];k++){
	  maps[j-1][k-1] = c[i];
	}
      }
    }
    /* for(int i=0;i<h;i++){
       for(int j=0;j<w;j++){
       cout << maps[i][j];
       }
       cout << endl;
       }*///マップ確認用
    if(solve(xs-1,ys-1))cout << "OK\n";
    else cout << "NG\n";
  }
}
int solve(int xs,int ys){
  if(xs < 0 || ys < 0 || xs > w-1 || ys > h-1 || maps[xs][ys] == 0){
    return 0;
  }
  else if(maps[xs][ys] == maps[xg-1][yg-1]){
    return 1;
  }
  if(maps[xs-1][ys] == maps[xs][ys]){
    return solve(xs-1,ys);
  }
  if(maps[xs][ys-1] == maps[xs][ys]){
    return solve(xs,ys-1);
  }
  if(maps[xs+1][ys] == maps[xs][ys]){
    return solve(xs+1,ys);
  }
  if(maps[xs][ys+1] == maps[xs][ys]){
    return solve(xs,ys+1);
  }
}

C++: #include <iostream>
using namespace std;
  
int F[102][102];
  
void DFS(int Y,int X,int c){
  if(F[Y][X] != c){
    return;
  }
  
  F[Y][X] = -2;
  DFS(Y-1,X  ,c);
  DFS(Y  ,X+1,c);
  DFS(Y+1,X  ,c);
  DFS(Y  ,X-1,c);
}
  
  
int main(){
  int w,h,xs,ys,xg,yg,n;
  while(1){
    cin >> w >> h;
    if(w == 0 && h == 0)
      break;

    for(int i=0; i<20; i++){
      for(int j=0; j<20; j++){
        F[i][j]=-1;
      }
    }
      
    cin >> 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(F[xs][ys] == 0){
    cout << "NG" << endl;
  } else {
    DFS(xs,ys,F[xs][ys]);
  
    if(F[xg][yg] == -1){
      cout << "OK" << endl;
    } else {
      cout << "NG" <<endl;
    }
  }

}
}

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

int xg,yg,c,a[1000][1000],memo[1000][1000],ans,p,w,h;

int solve(int ys,int xs){

  if(memo[ys][xs] < 0) return memo[ys][xs];

  if(ys + 1 <= w && a[ys+1][xs] == p) solve(ys+1,xs);
  else if(xs + 1 <= h && a[ys][xs+1] == p) solve(ys,xs+1);
  //else if(ys - 1 > 0 /*&& a[ys-1][xs] == p*/) solve(ys-1,xs);
  //else if(xs - 1 > 0 && a[ys][xs-1] == p) solve(ys,xs-1);

  if(xs == xg && ys == yg) return ans = 1;

  return  memo[ys][xs] = -1;
}

int main(){
  int xs,ys,n,d,x,y;

  while(true){
    cin >> w >> h;
    if(!w && !h) break;

    memset(a,0,sizeof(a));
    memset(memo,0,sizeof(memo));
    ans = 0;

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

    for(int i=0;i<n;i++){
      cin >> c >> d >> x >> y;

      if(d == 0){
	for(int i=y;i<y+2;i++){
	  for(int j=x;j<x+4;j++) a[i][j] = c;
	}
      }

      else if(d == 1){
	for(int i=y;i<y+4;i++){
	  for(int j=x;j<x+2;j++) a[i][j] = c;
	}
      }
    }

    p = a[yg][xg];
    solve(ys,xs);

    for(int i=1;i<=h;i++){
      cout << endl;
      for(int j=1;j<=w;j++) cout << a[i][j];
    }

    if(ans == 1)   cout << "OK" << endl;
    else if(ans == 0)cout << "NG" << endl;

  }
}

C++: #include<stdio.h>
#include<string.h>
#include<queue>
#include<utility>
using namespace std;
char m[128][128];
void PutSquare(int x, int y, int c)
{
	m[y][x] = m[y+1][x] = m[y+1][x+1] = m[y][x+1] = static_cast<char>(c);
}
bool CanReach(int sx,int sy,int gx,int gy)
{
	bool f[128][128]={};

	typedef pair<int,int>P;
	queue<P>q;
	q.push(P(sx,sy));

	const char c = m[sy][sx];
	if(!c)
		return false;
	const int dx[]={0,1,0,-1},dy[]={1,0,-1,0};
	while(!q.empty())
	{
		P p = q.front();
		q.pop();
		if(p.first==gx && p.second==gy)
			return true;
		if(f[p.second][p.first] || c!=m[p.second][p.first])
			continue;
		f[p.second][p.first] = true;
		for(int i=0; i<4; ++i)
			q.push(P(p.first+dx[i],p.second+dy[i]));
	}
	return false;
}
int main()
{
	int h, w;
	int sx, sy;
	int gx, gy;
	int n;
	int c, d, x, y;
	while(scanf("%d%d",&w,&h),h)
	{
		memset(m,0,sizeof(m));

		scanf("%d%d",&sx,&sy);
		scanf("%d%d",&gx,&gy);
		scanf("%d",&n);
		while(n--)
		{
			scanf("%d%d%d%d",&c,&d,&x,&y);
			PutSquare(x,y,c);
			if(d==0)
				PutSquare(x+2,y,c);
			else
				PutSquare(x,y+2,c);
		}
		puts(CanReach(sx,sy,gx,gy) ? "OK" :"NG");
	}
	return 0;
}