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<string>
#include<algorithm>
#include<list>
#include<set>
#include<map>
#include<queue>
#include<stack>
#include<numeric>
#include<vector>
#include<cstdio>
#include<climits>
#include<cfloat>
#include<cstring>
#define foreach(t,p,it) for(t::iterator it=p.begin(),it!=p.end(),++it)
#define all(p) p.begin(),p.end()
#define rep(i,n) for(int i=0;i<n;i++)
#define REP(n) rep(i,n)
using namespace std;

const int W=210,H = 210;
int block[W][H];
int ans;

int w,h,xs,ys,xg,yg,n,c,d,x,y;
void solve(int xi,int yi)
{
    if(block[xi][yi] == 0) return;

    if(xi==xg && yi==yg){ ans = 1; return;}
    if(block[xi][yi] == c)
    {
        block[xi][yi] = 0;
        solve(xi-1, yi);
        solve(xi, yi-1);
        solve(xi+1, yi);
        solve(xi, yi+1);
    }
    block[xi][yi] = 0;
    return;
}

int main()
{
    while(cin >> w >> h )
    {
        if(w==0 && h==0) break;
        memset(block,0,sizeof(int)*w*h);
        ans = 0;
        cin >> xs >> ys;
        cin >> xg >> yg;
        cin >> n;
        REP(n)
        {
            cin >> c >> d >> x >> y;
            //cout << x << ","<< y << endl;
            if(d==1) //tate
            {
                block[x][y] = c;
                block[x][y+1] =c;
                block[x][y+2] = c;
                block[x][y+3] = c;
                block[x+1][y] = c;
                block[x+1][y+1] = c;
                block[x+1][y+2] = c;
                block[x+1][y+3] = c;
            }
            else
            {
                block[x][y] = c;
                block[x+1][y] = c;
                block[x+2][y] = c;
                block[x+3][y] = c;
                block[x][y+1] = c;
                block[x+1][y+1] = c;
                block[x+2][y+1] = c;
                block[x+3][y+1] = c;
            }
        }
        c = block[xs][ys];
        solve(xs,ys);

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

    }

    return 0;
}

C++: #include<iostream>
#include<string>
#include<algorithm>
#include<list>
#include<set>
#include<map>
#include<queue>
#include<stack>
#include<numeric>
#include<vector>
#include<cstdio>
#include<climits>
#include<cfloat>
#include<cstring>
#define foreach(t,p,it) for(t::iterator it=p.begin(),it!=p.end(),++it)
#define all(p) p.begin(),p.end()
#define rep(i,n) for(int i=0;i<n;i++)
#define REP(n) rep(i,n)
using namespace std;

const int W=210,H = 210;
int block[W][H];
int ans;

int w,h,xs,ys,xg,yg,n,c,d,x,y;
void solve(int xi,int yi)
{
    if(xi==xg && yi==yg && block[xi][yi]==c){ ans = 1; return;}
    if(block[xi][yi] == 0) return;

    if(block[xi][yi] == c)
    {
        block[xi][yi] = 0;
        solve(xi-1, yi);
        solve(xi, yi-1);
        solve(xi+1, yi);
        solve(xi, yi+1);
    }
    block[xi][yi] = 0;
    return;
}

int main()
{
    while(cin >> w >> h )
    {
        memset(block,0,sizeof(int)*W*H);
        if(w==0 && h==0) break;
        ans = 0;
        cin >> xs >> ys;
        cin >> xg >> yg;
        cin >> n;
        REP(n)
        {
            cin >> c >> d >> x >> y;
            if(d == 1) //tate
            {
                block[x][y] = c;
                block[x][y+1] =c;
                block[x][y+2] = c;
                block[x][y+3] = c;
                block[x+1][y] = c;
                block[x+1][y+1] = c;
                block[x+1][y+2] = c;
                block[x+1][y+3] = c;
            }
            else
            {
                block[x][y] = c;
                block[x+1][y] = c;
                block[x+2][y] = c;
                block[x+3][y] = c;
                block[x][y+1] = c;
                block[x+1][y+1] = c;
                block[x+2][y+1] = c;
                block[x+3][y+1] = c;
            }
        }
        /*rep(j,h)
        {
            rep(i,w) cout << block[i+1][j+1] << " " ;
            cout << endl;
        }*/

        c = block[xs][ys];
        //cout << c  << " goal" << block[xg][yg]<< endl;
        solve(xs,ys);

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

    return 0;
}

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

int F[105][105];
int xg,yg;


void DFS(int Y,int X,int c){
  if(F[Y][X] != c){
    return;
  }

  F[Y][X] = -1;
  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,n;
  while(1){
    cin >> w >> h;
    if(w == 0 && h == 0)
      break;

      for(int i=0;i<105;i++){
        for(int j=0;j<105;j++){
                F[i][j]=0;
        }
      }
    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;
        }
      }
    }

  DFS(xs,ys,F[xs][ys]);
  if(F[xg][yg] == -1){
    cout << "OK" << endl;
  } else {
    cout << "NG" <<endl;
  }
  }
}