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 <algorithm>
#include <queue>
#include <utility>
#include <string>
#include <cstdlib>

using namespace std;

typedef pair<int,int> Pa;
int dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};

string bfs(int a[101][101], int sx, int sy, int gx, int gy, int w, int h)
{
	int s, t, m = a[sy][sx];
	bool vis[101][101];
	string str = "NG";
	queue<Pa> que;
	Pa pa;
	fill(&vis[0][0], &vis[h+1][w+1], true);
	
	que.push(Pa(sy, sx));
	vis[sy][sx] = false;
	
	while(!que.empty()){
		pa = que.front();
		que.pop();
		if(pa.first == gy && pa.second == gx){
			str = "OK";
			break;
		}
		
		for(int i = 0; i < 4; i++){
			s = pa.first + dy[i];
			t = pa.second + dx[i];
			if(1 <= s && s <= h && 1 <= t && t <= w){
				if(vis[s][t] && m == a[s][t]){
					que.push(Pa(s, t));
					vis[s][t] = false;
				}
			}
		}
	}
	
	return str;
}

int main()
{
	int a[101][101], w, h, sx, sy, gx, gy, s, t, u, v, n;
	
	while(1){
		cin >> w >> h;
		if(w == 0 && h == 0){
			break;
		}
		fill(&a[0][0], &a[h+1][w+1], -1);
		cin >> sx >> sy;
		cin >> gx >> gy;
		cin >> n;
		
		while(n--){
			cin >> s >> t >> u >> v;
			if(t == 0){
				for(int i = v; i <= v+1; i++){
					for(int j = u; j <= u+3; j++){
						a[i][j] = s;
					}
				}
			} else {
				for(int i = v; i <= v+3; i++){
					for(int j = u; j <= u+1; j++){
						a[i][j] = s;
					}
				}
			}
		}
		
		cout << bfs(a, sx, sy, gx, gy, w, h) << endl;
	}
	
	return 0;
}

C++: #include <iostream>
using namespace std;
  
int F[105][105];
int xg,yg,w,h;
  
  
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-1  ,X,c);
  DFS(Y,X+1  ,c);
  DFS(Y  ,X-1,c);
}
  
  
int main(){
  int 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] = 10;
      }
    }
      
    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;
  }
  }
}

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

int main(){
	int w, h, xs, ys, xg, yg, n, c, d, x, y, color;
	vector< vector< int > > field;
	queue< complex< int > > que;
	bool exist;
	
	while(cin >> w >> h, w){
		cin >> xs >> ys >> xg >> yg >> n;
		field.clear();
		
		field.resize(w);
		for(int i = 0; i < w; ++i) field[i].resize(h);
		
		for(int i = 0; i < n; ++i){
			cin >> c >> d >> x >> y;
			
			if(d == 0){
				for(int j = 0; j < 4; ++j){
					for(int k = 0; k < 2; ++k){
						field[x + j - 1][y + k - 1] = c;
					}
				}
			}else{
				for(int j = 0; j < 2; ++j){
					for(int k = 0; k < 4; ++k){
						field[x + j - 1][y + k - 1] = c;
					}
				}
			}
		}
		
		exist = false;
		if(field[xs - 1][ys - 1] != 0){
			que.push(complex< int >(xs - 1, ys - 1));
			color = field[xs - 1][ys - 1];
			
			while(!que.empty()){
				complex< int > pos = que.front();
				que.pop();
				
				if(pos.real() == xg - 1 && pos.imag() == yg - 1){
					exist = true;
					break;
				}
				
				if(pos.real() > 0 && field[pos.real() - 1][pos.imag()] == color) que.push(pos + complex< int >(-1, 0));
				if(pos.real() < w - 1 && field[pos.real() + 1][pos.imag()] == color) que.push(pos + complex< int >(1, 0));
				if(pos.imag() > 0 && field[pos.real()][pos.imag() - 1] == color) que.push(pos + complex< int >(0, -1));
				if(pos.imag() < h - 1 && field[pos.real()][pos.imag() + 1] == color) que.push(pos + complex< int >(0, 1));
				
				field[pos.real()][pos.imag()] = 0;
			}
		}
		
		cout << (exist ? "OK" : "NG") << endl;
		
	}
	
	return 0;
}

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

int w,h;
int field[101][101];
int gx,gy;
int sc;
bool search(int x,int y)
{
	bool flag = false;
	if(x == gx && y == gy)
		flag = true;
	else{
		int vectorx[4] = {-1,0,1,0},vectory[4] = {0,-1,0,1};
		for(int i=0;i<4;i++){
			if(x+vectorx[i] >= 0 && y+vectory[i] >= 0 && x+vectorx[i] < w && y+vectory[i] < h){
				if(field[x+vectorx[i]][y+vectory[i]] == sc){
					field[x][y] = 0;
					flag |= search(x+vectorx[i],y+vectory[i]);
				}
			}
		}
	}
	return flag;
}
int main()
{
	while(cin >> w >> h){
		if(w == 0 && h == 0)
			break;
		int sx,sy;
		cin >> sx >> sy;
		cin >> gx >> gy;
		int n,c,x,y;
		bool d;
		cin >> n;
		for(int i=0;i<n;i++){
			cin >> c >> d >> x >> y;
			int vectorx,vectory;
			if(d == 0){
				vectorx = 4;vectory = 2;
			}else{
				vectorx = 2;vectory = 4;
			}
			for(int j=0;j<vectorx;j++){
				for(int k=0;k<vectory;k++){
					field[x+j][y+k] = c;
				}
			}
		}
		sc = field[sx][sy];
		if(search(sx,sy))
			cout << "OK" << endl;
		else
			cout << "NG" << endl;
	}
	return 0;
}