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 vx[4]={1,0,-1,0};int vy[4]={0,1,0,-1};int flag=0;int board[102][102]={0};vector<pair<int,int> > com;
queue<pair<pair<int,int>,int > > qp;int num=0;
pair<pair<int,int>,int > now;
int check(int i){
  if(now.second!=board[now.first.second+vy[i]][now.first.first+vx[i]])
    return 0;
  for(int j=0;j<com.size();j++)
    if(now.first.second+vy[i]==com[j].second&&now.first.first+vx[i]==com[j].first)
      return 0;
  return 1;
}
int main(){
  int w,h;
  while(cin>>w>>h,w+h!=0){
    flag=0;num=0;
    com.clear();
    while(!qp.empty())
      qp.pop();
    int xs,ys,xg,yg;
    for(int i=0;i<h+2;i++)
      for(int j=0;j<w+2;j++)
	board[i][j]=0;
    cin>>xs>>ys;cin>>xg>>yg;
    int n,c,d,x,y;
    cin>>n;
    for(int i=0;i<n;i++){
      cin>>c>>d>>x>>y;
      for(int j=0;j<2;j++){
	for(int k=0;k<4;k++){
	  if(d==0)
	    board[y+j][x+k]=c;
	  else
	    board[y+k][x+j]=c;
	}
      }
    }
    qp.push(make_pair(make_pair(xs,ys),board[ys][xs]));
    while(!qp.empty()){
      now=qp.front();
      qp.pop();
      for(int i=0;i<4;i++){
	num++;
	if(check(i)==1){
	  qp.push(make_pair(make_pair(now.first.first+vx[i],now.first.second+vy[i]),now.second));
	  com.push_back(make_pair(now.first.first+vx[i],now.first.second+vy[i]));
	  if(now.first.first+vx[i]==xg&&now.first.second+vy[i]==yg){
	    flag=1;
	    break;
	  }
	}
      }
      if(flag==1){cout<<"OK"<<endl;break;}
      if(num==5000||flag==0){cout<<"NG"<<endl;break;}
    }
  }
  return 0;
}

C++: #include<stdio.h>

int w,h;
int masu[100][100];
int uramasu[100][100];
int stx,sty;
int gox,goy;
int flg;

void saiki(int x,int y,int col){
	
	if(x==gox && y==goy){
		flg=1;
	}
	
	if(x+1<w && masu[x+1][y]==col && uramasu[x+1][y]==0){
		uramasu[x+1][y]=1;
		saiki(x+1,y,col);
	}
	
	if(y+1<h && masu[x][y+1]==col && uramasu[x][y+1]==0){
		uramasu[x][y+1]=1;
		saiki(x,y+1,col);
	}
	
	if(x-1>=0 && masu[x-1][y]==col && uramasu[x-1][y]==0){
		uramasu[x-1][y]=1;
		saiki(x-1,y,col);
	}
	
	if(y-1>=0 && masu[x][y-1]==col && uramasu[x][y-1]==0){
		uramasu[x][y-1]=1;
		saiki(x,y-1,col);
	}
}

int main(void){
	while(1){
		
		scanf("%d%d",&w,&h);
		flg=0;
		if(w==0){
			break;
		}
		scanf("%d%d",&stx,&sty);
		scanf("%d%d",&gox,&goy);
		int n;
		scanf("%d",&n);
		
		for(int i=0;i<100;i++){
			for(int j=0;j<100;j++){
				masu[i][j]=0;
				uramasu[i][j]=0;
			}
		}
		for(int i=0;i<n;i++){
			int c,d,x,y;
			scanf("%d%d%d%d",&c,&d,&x,&y);
			switch(d){
				case 0:
				for(int i=0;i<4;i++){
					for(int j=0;j<2;j++){
						masu[i+x][j+y]=c;
					}
				}break;
				
				case 1:
				for(int i=0;i<2;i++){
					for(int j=0;j<4;j++){
						masu[i+x][j+y]=c;
					}
				}
			}
		}
		
		saiki(stx,sty,masu[stx][sty]);
		
		if(flg==0){
			puts("NG");
		}else{
			puts("OK");
		}
		
		/*
		for(int i=0;i<w;i++){
			for(int j=0;j<h;j++){
				if(masu[j][i]==0){
					printf(" ");
					continue;
				}
				printf("%d ",masu[j][i]);
			}
			puts("");
		}*/
	}
	
}

C++: #include<cstdio>
#include<iostream>
#include<algorithm>
#include<string>
#include<queue>
#include<vector>
#include<functional>
#include<cmath>
#include<map>
#include<stack>
#include<set>
#include<numeric>
#include<limits>

#define all(x) (x).begin(),(x).end()
#define rall(x) (x).rbegin(),(x).rend()

using namespace std;
typedef long long ll;
typedef pair<int, int> pi;
typedef pair<ll, ll> pl;
typedef pair<ll, char> plc;

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

int check(int xs, int ys, int xg, int yg ,int c, int board[110][110]) {
	int used[110][110] = { 0 };
	queue<pl> q;
	q.push({ xs, ys });

	while (!q.empty()) {
		int x = q.front().first;
		int y = q.front().second;
		q.pop();
		for (int i = 0; i < 4; i++) {
			int ddx = dx[i] + x;
			int ddy = dy[i] + y;
			if (ddx >= 1 && ddx <= w && ddy >= 1 && ddy <= h && !used[ddy][ddx]) {
				used[ddy][ddx] = 1;
				if (board[ddy][ddx] == c && ddy == yg && ddx == xg)return 1;
				else if (board[ddy][ddx] == c) {
					q.push({ddx,ddy});
				}
			}
		}
	}
	return 0;
}

int main()
{
	while (cin >> w >> h, w, h) 
	{
		int xs, ys, xg, yg;
		int n;
		int board[110][110] = { 0 };
		cin >> xs >> ys >> xg >> yg;
		cin >> n;
		for (int i = 0; i < n; i++)
		{ 
			int c,d, x, y;
			cin >> c >> d >> x >> y;
			if (!d){
				for (int i = y; i < y+2; i++) {
					for (int j = x; j < x+4; j++) 
						board[i][j] = c;
				}
			}
			else {
				for (int i = y; i < y+4; i++) {
					for (int j = x; j < x+2; j++)
						board[i][j] = c;
				}
			}
		}
		if (check(xs, ys, xg, yg, board[ys][xs], board))
			cout << "OK" << endl;
		else
			cout << "NG" << endl;
	}
	return 0;
}

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

int a=0;
int F[102][102];
void DFS(int Xs,int Ys,int c,int Xg,int Yg){
  if(F[Xs][Ys]!=c){
    return;
  }else if(Xs==Xg&&Ys==Yg){
    a=1;
    return;
  }
 F[Xs][Ys]=0;
 DFS(Xs-1,Ys,c,Xg,Yg);
 DFS(Xs,Ys-1,c,Xg,Yg);
 DFS(Xs+1,Ys,c,Xg,Yg);
 DFS(Xs,Ys+1,c,Xg,Yg);
}

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