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 Board[102][102];    //Board[j, x][i, y]
bool isOK;
int xs, ys, xg, yg;

void DFS(int c, int x, int y){
    if(Board[x][y] != c){
        return;
    }
    else if(x==xg && y==yg){
        isOK = true;
        return;
    }

    Board[x][y] = 0;

    DFS(c, x+1, y  );
    DFS(c, x  , y+1);
    DFS(c, x-1, y  );
    DFS(c, x  , y-1);
}

int main(){
    int w,h;
    while(true){
        cin >> w >> h;
        if(w==0 && h==0)
            break;
        
        isOK = false;
        for(int i=0;i<102;i++){
            for(int j=0;j<102;j++)
                Board[j][i] = 0;
        }
        cin >> xs >> ys >> xg >> yg;

        int n, c, d, x, y;
        cin >> n;
        for(int t=0;t<n;t++){
            cin >> c >> d >> x >> y;
            int wb = 2, hb = 2;
            d?hb:wb = 4;
            for(int i=0;i<hb;i++){
                for(int j=0;j<wb;j++)
                    Board[x+j][y+i] = c;
            }
        }

        DFS(Board[xs][ys], xs, ys);

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

    }

    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std ;

#define pb(n) push_back(n)
#define fi first
#define se second
#define all(r) begin(r),end(r)
#define vmax(ary) *max_element(all(ary))
#define vmin(ary) *min_element(all(ary))
#define debug(x) cout<<#x<<": "<<x<<endl
#define fcout(n) cout<<fixed<<setprecision((n))
#define scout(n) cout<<setw(n)
#define vary(type,name,size,init) vector< type> name(size,init)
#define vvl(v,w,h,init) vector<vector<ll>> v(w,vector<ll>(h,init))
#define mp(a,b) make_pair(a,b)

#define rep(i,n) for(int i = 0; i < (int)(n);++i)
#define REP(i,a,b) for(int i = (a);i < (int)(b);++i)
#define repi(it,array) for(auto it = array.begin(),end = array.end(); it != end;++it)
#define repa(n,array) for(auto &n :(array))

using ll = long long;
using pii = pair<int,int> ;
using pll = pair<ll,ll> ;

const int mod = 1000000007;
constexpr ll inf = ((1<<30)-1)*2+1 ;
constexpr double PI = acos(-1.0) ;
double eps = 1e-10 ;
const int dy[] = {-1,0,1,0,1,-1,1,-1};
const int dx[] = {0,-1,0,1,1,-1,-1,1};

inline bool value(int x,int y,int w,int h){
  return (x >= 0 && x < w && y >= 0 && y < h);
}
int xs,ys,xg,yg,n;
ll w,h;
vector<vector<ll>> field;
vector<vector<ll>> f;
bool res = false;

void dfs(int x,int y,int c){
  if(f[x][y] != inf) return ;
  if(x == xg && y == yg){
    res = true;
    return ;
  }
  f[x][y] = 1;
  rep(i,4){
    int nx = x + dx[i],ny = y + dy[i];
    if(value(nx,ny,w,h) && field[nx][ny] == c){
      dfs(nx,ny,c);
    }
  }
  return ;
}

void solve(){
  f = vector<vector<ll>>(w+1,vector<ll>(h+1,inf));
  res = false;
  if(field[xs][ys] != inf){
    dfs(xs,ys,field[xs][ys]);
  }
  if(res){
    cout << "OK" << endl;
    return ;
  }
  cout << "NG" << endl;
}

int main(){
  cin.tie(0);
  ios::sync_with_stdio(false);
  while(cin >> w >> h && w+h){
    field = vector<vector<ll>>(w+1,vector<ll>(h+1,inf));
    cin >> xs >> ys >> xg >> yg >> n;
    xs--,ys--,xg--,yg--;
    int c,d,x,y;
    rep(i,n){
      cin >> c >> d >> x >> y;
      --x,--y,--c;
      rep(j,2){
        rep(k,4){
          ll nx = k,ny = j;
          if(d){
            swap(nx,ny);
          }
          field[x+nx][y+ny] = c;
        }
      }
    }
    solve();
  }
  return 0;
}

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

int xs,ys,c,a[105][105],memo[105][105],ans,p,w,h;

int solve(int yg,int xg){

  if(a[yg][xg] != p) return 0;

  a[yg][xg] = 0;

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

  else if(yg - 1 > 0 && a[yg-1][xg] == p) solve(yg-1,xg);
  else if(xg - 1 > 0 && a[yg][xg-1] == p) solve(yg,xg-1);
  else if(yg + 1 <= w && a[yg+1][xg] == p) solve(yg+1,xg);
  else if(xg + 1 <= h && a[yg][xg+1] == p) solve(yg,xg+1);
}

int main(){
  int xg,yg,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(yg,xg);

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

  }
}

C++: #include<iostream>
#include<algorithm>
using namespace std;
int field[101][101],b[101][101],X,Y,n,dx[4]={0,1,0,-1},dy[4]={1,0,-1,0},I,sX,sY,gX,gY,ans,sgc;
int func(int x,int y){
	for(I=0;I<4;I++){
		int xx=x+dx[I];
		int yy=y+dy[I];
		if(xx>0&&yy>0&&xx<=X&&yy<=Y&&field[xx][yy]==sgc&&b[xx][yy]==0){
			if(xx==gX&&yy==gY){
				if(ans==-1)ans=b[x][y];
				return 0;
			}
			else{
			b[xx][yy]=b[x][y]+1;
			func(xx,yy);
			}
		}
	}
	return 0;
}
int main(){
	int i,i2,c,d,x,y;
	cin>>X>>Y;
	while(X!=0){
		cin>>sX>>sY>>gX>>gY>>n;
		ans=-1;
		for(i=1;i<=100;i++){
			c=0;
			d=0;
			x=0;
			y=0;
			for(i2=1;i2<=100;i2++){
				field[i][i2]=0;
				b[i][i2]=0;
			}
		}
		for(i=1;i<=n;i++){
			cin>>c>>d>>x>>y;
			if(d==0){
				field[x][y]=c;
				field[x+1][y]=c;
				field[x+2][y]=c;
				field[x+3][y]=c;
				field[x][y+1]=c;
				field[x+1][y+1]=c;
				field[x+2][y+1]=c;
				field[x+3][y+1]=c;
			}
			else{
				field[x][y]=c;
				field[x][y+1]=c;
				field[x][y+2]=c;
				field[x][y+3]=c;
				field[x+1][y]=c;
				field[x+1][y+1]=c;
				field[x+1][y+2]=c;
				field[x+1][y+3]=c;
			}
		}
		/*for(i=1;i<=Y;i++){
			for(i2=1;i2<=X;i2++)cout<<field[i2][i]<<' ';
			cout<<endl;
		}*/
		sgc=field[sX][sY];
		func(sX,sY);
		/*for(i=1;i<=Y;i++){
			for(i2=1;i2<=X;i2++){
				if(b[i2][i]<10)cout<<' '<<b[i2][i]<<' ';
				else cout<<b[i2][i]<<' ';
			}
			cout<<endl;
		}*/
		if(ans==-1)cout<<"NG"<<endl;
		else cout<<"OK"<<endl;
		cin>>X>>Y;
	}
}