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<vector>
#include<string>
#define ll long long
#define loop(i,n) for (int i = 0; i < n; i++)
#define loops(i,f,n) for (int i = (f); i < n; i++)
#define INF 100000000000000
#define sort(a) sort(a.begin(),a.end())
#define rsort(a) sort(a.rbegin(),a.rend())
using namespace std;
int w, h, sx, sy, gx, gy, n;
vector <vector<int > > grid(105, vector<int>(105));
vector <vector<bool > > grid_visited(105, vector<bool>(105, false));
void input(int c, int d, int x, int y)
{
    if (d == 0)//yokonaga
    {
        loop(i, 2)
        {
            loop(j, 4)
            {
                grid[y + i][x + j] = c;
            }
        }
    }
    else//tatenaga
    {
        loop(i, 4)
        {
            loop(j, 2)
            {
                grid[y + i][x + j] = c;
            }
        }
    }
}
    bool a=false;
bool dfs(int nx, int ny)
{
    if (nx == gx&&ny == gy)return true;
    if (nx < 0 || ny < 0 || nx >= h || ny >= w || grid[nx][ny] == 0 || grid_visited[nx][ny])return false;
    grid_visited[nx][ny] = true;
    if((nx+1) >= 0 && ny >= 0 && (nx+1) < h && ny < w)if(grid[nx + 1][ny]== grid[nx][ny])a|=dfs(nx + 1, ny);
    if(nx >= 0 && (ny+1) >= 0 && nx < h && (ny+1) < w)if(grid[nx][ny+1]== grid[nx][ny])a|=dfs(nx, ny+1);
    if((nx-1) >= 0 && ny >= 0 && (nx-1) < h && ny < w)if(grid[nx - 1][ny]== grid[nx][ny])a|=dfs(nx - 1, ny);
    if(nx >= 0 && (ny-1) >= 0 && nx < h && (ny-1) < w)if(grid[nx][ny-1]== grid[nx][ny])a|=dfs(nx, ny-1);
    //return (dfs(nx + 1, ny) || dfs(nx, ny + 1) || dfs(nx - 1, ny) || dfs(nx, ny - 1));
    return a;
    return false;
}
int main()
{
    while (1)
    {
        cin >> w >> h;
        if (!w && !h) break;
        else
        {
            cin >> sx >> sy >> gx >> gy >> n;
            sx--; sy--; gx--; gy--;
            loop(i, n)
            {
                int c, d, x, y;
                cin >> c >> d >> x >> y;
                x--; y--;
                input(c, d, x, y);
            }
            /*loop(i, h)
            {
                loop(j, w)
                {
                    cout << grid[i][j] << " ";
                }
                cout << endl;
            }*/
            a=false;
            
            cout << (dfs(sx, sy) ? "OK" : "NG") << endl;
        }
    }
 
}

C++: #include <iostream>
using namespace std;
   
int F[102][102];
int xg,yg,w,h;
   
   
void DFS(int Y,int X,int c){
  //if(Y < 1 || X < 1)
    //return;
  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<102; i++){
      for(int j=0; j<102; 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(c == 0)
         c = 1919810;
      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<iostream>
using namespace std ;

int w , h ;
int gx , gy , color , ans ;
int map[101][101] = {} ;
int dx[] = { 0,1,0,-1 } ;
int dy[] = { 1,0,-1,0 } ;

void judge( int nx , int ny ){
	if( nx==gx && ny==gy ) ans = 1 ;
	
	map[nx][ny] = 0 ;
	
	for( int i=0 ; i<4 ; i++ ){
		if( nx+dx[i]>0 && nx+dx[i]<=w && ny+dy[i]>0 && ny+dy[i]<=h )
			if( map[nx+dx[i]][ny+dy[i]] == color )
				judge( nx+dx[i] , ny+dy[i] ) ;
	}
}

int main(){
	
	int sx , sy ;
	int n ;
	int c , d , x , y ;
	int a , b ;
	
	while(1){
		cin >> w >> h ;
		if( w==0 && h==0 ) break;
		
		cin >> sx >> sy ;
		cin >> gx >> gy ;
		cin >> n ;
		
		for( int i=0 ; i<n ; i++ ){
			cin >> c >> d ;
			cin >> x >> y ;
			if( d==0 ){
				a = 4 ;
				b = 2 ;
			}else {
				a = 2 ;
				b = 4 ;
			}
			
			for( int j=x ; j<=x+a ; j++ ){
				for( int k=y ; k<=y+b ; k++ ){
					map[j][k] = c ;
					if( sx==j && sy==k ) color = c ;
				}
			}
		}
		
		ans = 0 ;
		judge( sx , sy ) ;
		
		if( ans == 1 ) cout << "OK" << endl ;
		else cout << "NG" << endl ;
		
		for( int i=1 ; i<w ; i++ )
			for( int j=1 ; j<h ; j++ )
				map[i][j] = 0 ;
	}
	
return 0;
}