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<cstdio>
#include<iostream>
#include<algorithm>
#define int long long
using namespace std;
int w,h,xs,ys,xg,yg,n,c,d,x,y,nok,sc;
int fld[101][101];
int dx[]={0,1,0,-1},dy[]={1,0,-1,0};
void dfs(int fx,int fy){
    if(fld[fy][fx]!=sc||nok==1||fx<0||fx>w||fy<0||fy>h)return;
    if(fx==xg-1&&fy==yg-1){
        if(sc==fld[fy][fx])nok=1;
    }
    fld[fy][fx]=0;
    for(int i=0;i<4;i++){
        dfs(fx+dx[i],fy+dy[i]);
    }
}
signed main(){
    for(;;){
        cin>>w>>h;
        if(w==0&&h==0)break;
        cin>>xs>>ys;
        cin>>xg>>yg;
        cin>>n;
        nok=0;
        fill(fld[0],fld[0]+101,0);
        for(int i=0;i<n;i++){
            cin>>c>>d>>x>>y;
            x--,y--;
            if(d==0){
                for(int j=0;j<2;j++){
                    for(int k=0;k<4;k++){
                        fld[y+j][x+k]=c;
                    }
                }
            }
            if(d==1){
                for(int j=0;j<4;j++){
                    for(int k=0;k<2;k++){
                        fld[y+j][x+k]=c;
                    }
                }
            }
        }
        sc=fld[ys][xs];
        dfs(0,0);
        if(nok==1)cout<<"OK"<<endl;
        else cout<<"NG"<<endl;
    }
    return 0;
}

C++: #include<iostream>
#include<string>
#include<vector>
#include<utility>
#include<queue>
#include<algorithm>
#include<cmath>
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<complex>
#define INF 2147483647
#define llINF 9223372036854775807
#define pb push_back
#define mp make_pair 
#define F first
#define S second
#define ll long long

using namespace std;
int main(){
  int w,h;
  while(cin>>w>>h,w+h){
    int xs,ys,xg,yg;
    bool Map[h+10][w+10]={};
    bool flag=false;
    cin>>xs>>ys>>xg>>yg;
    xs--;ys--;xg--;yg--;
    int n;cin>>n;
    int Map2[h+10][w+10]={};
    Map[ys][xs]=true;
    queue<pair<int,int> >que;
    que.push(mp(ys,xs));
    for(int i=0;i<n;i++){
      int c,d,x,y;
      cin>>c>>d>>x>>y;
      x--;y--;
      if(d==0){
	for(int i=y;i<y+2;i++)
	  for(int j=x;j<x+4;j++)
	    Map2[i][j]=c;
      }else if(d==1){
	for(int i=y;i<y+4;i++)
	  for(int j=x;j<x+2;j++)
	    Map2[i][j]=c;
      }
    }
    for(int i=0;i<h;i++){
      for(int j=0;j<w;j++)
	cout<<Map2[i][j]<<" ";
      cout<<endl;
    }
    int vx[4]={0,-1,0,1};
    int vy[4]={1,0,-1,0};
    while(!que.empty()){
      pair<int,int>now=que.front();
      que.pop();
      if(now.F==yg&&now.S==xg){
	flag=true;
	break;
      }
      for(int kk=0;kk<4;kk++){
	int as=now.F+vx[kk];int bs=now.S+vy[kk];
	if(as<h&&as>=0&&bs<w&&bs>=0&&Map2[now.F][now.S]==Map2[as][bs]&&!Map[as][bs]){
	  que.push(mp(as,bs));
	  Map[as][bs]=true;
	}
      }
    }
    if(flag)
      cout<<"OK"<<endl;
    else
      cout<<"NG"<<endl;
  }
  return 0;
}

C++: #include<bits/stdc++.h>
#define range(i,a,b) for(int i = (a); i < (b); i++)
#define rep(i,b) range(i,0,b)
#define pb(a) push_back(a)
#define all(a) (a).begin(), (a).end()
#define debug(x) cout << "debug " << x << endl;
using namespace std;

bool isMaze;
int blocks[105][105], xg, yg, w,h;

void dfs(int target, int x, int y){
    if(x < 0 || y < 0 || x >= w || y >= h) return;
    if(x == xg && y == yg){
        isMaze = true;
        return;
    }
    if(blocks[y][x] != target || blocks[y][x] == 0){
        return;
    }

    blocks[y][x] = 0;
    
    dfs(target, x + 1, y);
    dfs(target, x - 1, y);
    dfs(target, x, y + 1);
    dfs(target, x, y - 1);
}

int main(){
    int xs, ys, n;
    while(cin >> w >> h, w||h){
        rep(i,105) rep(j,105) blocks[i][j] = 0;
        cin >> xs >> ys >> xg >> yg >> n;
        xs--; ys--; xg--; yg--;
        rep(i,n){
            int c, d, x, y;
            cin >> c >> d >> x >> y;
            x--; y--;
            if(d == 0){
                rep(j,2) rep(k,4) blocks[y + j][x + k] = c;
            }else{
                rep(j,4) rep(k,2) blocks[y + j][x + k] = c;
            }
        }
        isMaze = false;
        dfs(blocks[ys][xs], xs, ys);

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

C++: #include<bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
#define mp make_pair
#define fr first
#define sc second
#define Rep(i,n) for(int i=0;i<(n);i++)
#define Rrep(i, m, n) for(int i=(m);i<(n);i++)
#define All(v) v.begin(),v.end()
#define Uniq(v) v.erase(unique(All(v)),v.end())
typedef pair<int, int> Pii;
typedef pair<int, Pii> Pip;
typedef pair<string, int> Psi;
typedef vector<int> Vi;
const int INF = (1<<30);
const int dx[]={1,0,-1,0}, dy[]={0,-1,0,1};

int space[100][100];
bool flag[100][100];
int w, h;
int sx, sy;
int gx, gy;
int n;

bool bfs() {
  queue<Pii> q;
  int start_color = space[sy][sx];
  q.push( Pii(sy, sx) );

  while( !q.empty() ) {
    Pii p = q.front(); q.pop();
    int x = p.sc, y = p.fr;
    flag[y][x] = true;
    if( x == gx && y == gy ) return true;
    Rep(i, 4) {
      int nx = x+dx[i], ny = y+dy[i];
      if( nx >= 0 && ny >= 0 && nx < w && ny < h && !flag[ny][nx] && space[ny][nx] == start_color ) {
	q.push( Pii(ny, nx) );
      }
    }
  }

  return false; 
}

int main()
{
  while( cin >> w >> h, w+h ) {
    fill_n(*space, 100*100, 0);
    fill_n(*flag, 100*100, false);
    cin >> sx >> sy; sx--; sy--;
    cin >> gx >> gy; gx--; gy--;
    cin >> n;

    Rep(i, n) {
      int c, d, x, y;
      cin >> c >> d >> x >> y;
      x--; y--;
      if( d == 0 ) {
	Rep(j, 2) {
	  Rep(k, 4) {
	    space[y+j][x+k] = c;
	  }
	}
      } else {
	Rep(j, 4) {
	  Rep(k, 2) {
	    space[y+j][x+k] = c;
	  }
	}
      }
    }

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

}