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<bits/stdc++.h>
using namespace std;
#define ANSWER(x) cout<<x<<endl
#define debug(x) cout<<#x<<": "<<x
const int BA = 1000;
const int INFTY = (1<<21);
int xg,yg,w,h;
int maps[101][101];
int solve(int xs,int ys);
int main(){
  int tate[2] = {2,4};
  int yoko[2] = {4,2};
  int xs,ys,n;
  int c[101],d[101],x[101],y[101];
  while(1){
    fill(maps[0],maps[101],0);
    cin >> w >> h;
    if(!w && !h)break;
    cin >> xs >> ys >> xg >> yg >> n;
    for(int i=0;i<n;i++){
      cin >> c[i] >> d[i] >> x[i] >> y[i];
    }
    for(int i=0;i<n;i++){
      for(int j=y[i];j<y[i]+tate[d[i]];j++){
	for(int k=x[i];k<x[i]+yoko[d[i]];k++){
	  maps[j-1][k-1] = c[i];
	}
      }
    }
    /* for(int i=0;i<h;i++){
       for(int j=0;j<w;j++){
       cout << maps[i][j];
       }
       cout << endl;
       }*///マップ確認用
    if(solve(xs-1,ys-1))cout << "OK\n";
    else cout << "NG\n";
  }
}
int solve(int xs,int ys){
  if(xs < 0 || ys < 0 || xs > w-1 || ys > h-1 || maps[xs][ys] == 0){
    return 0;
  }
  else if(maps[xs][ys] == maps[xg-1][yg-1]){
    return 1;
  }
  if(maps[xs-1][ys] == maps[xs][ys]){
    return solve(xs-1,ys);
  }
  if(maps[xs][ys-1] == maps[xs][ys]){
    return solve(xs,ys-1);
  }
  if(maps[xs+1][ys] == maps[xs][ys]){
    return solve(xs+1,ys);
  }
  if(maps[xs][ys+1] == maps[xs][ys]){
    return solve(xs,ys+1);
  }
}

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

int a[1000][1000],memo[1000][1000];
int xg,yg,w,h,ans;

int solve(int xs,int ys){

  if(xs == xg && ys == yg) return ans = 1;
  if(memo[ys][xs] == 1) return memo[ys][xs];
  memo[ys][xs] = 1;
  a[ys][xs] = -1;

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

}

int main(){

  int xs,ys;
  int n;

  while(1){
    cin >> w >> h;
    if(!w && !h) break;
    cin >> xs >> ys >> xg >> yg >> n;

    memset(a,0,sizeof(a));
    memset(memo,0,sizeof(memo));
    ans = 0;

    int c,d,x,y;

    for(int i=0;i<n;i++){
      cin >> c >> d >> x >> y;

      if(d == 0){
	for(int j=0;j<4;j++){
	  a[y][x+j] = c;
	  a[y+1][x+j] = c;
	}
      }

      else if(d == 1){
	for(int j=0;j<4;j++){
	  a[y+j][x] = c;
	  a[y+j][x+1] =c ;
	}
      }
    }

    solve(xs,ys);

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

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

int C[102][102];

void meiro(int W,int H,int c){
 if(C[W][H]!=c){
   return;
 }

 C[W][H] = -1;

 meiro(W-1,H  ,c);
 meiro(W  ,H+1,c);
 meiro(W+1,H  ,c);
 meiro(W  ,H-1,c);
}

int main(){
 while(1){
   int w,h;
   cin >> w >> h;
   if(w==0 && h==0){
     break;
   }

   for(int i=0;i<20;i++){
     for(int j=0;j<20;j++){
       C[i][j] = 0;
     }
   }

   int xs,ys,xg,yg;
   cin >> xs >> ys >> xg >> yg;

   int n;
   cin >> n;

   int c,d,x,y;
   for(int i=0;i<n;i++){
     cin >> c >> d >> x >> y;

     if(d==0){
       for(int j=x;j<x+4;j++){
         for(int k=y;k<y+2;k++){
           C[j][k]=c;
         }
       }
     }else{
       for(int j=x;j<x+2;j++){
         for(int k=y;k<y+4;k++){
           C[j][k]=c;
         }
       }
     }
   }
if(C[xs][ys] == 0){
cout << "NG"<<endl;
continue;
}
   meiro(xs,ys,C[xs][ys]);
   //print(w,h);

   if(C[xg][yg] == -1){
     cout << "OK" << endl;
   }else{
     cout << "NG" << endl;
   }
 }

 return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
const int limit = 100;
int w, h, n;
int xs, ys, xg, yg;
int maze[limit][limit];
int dx[4] = {1, -1, 0, 0};
int dy[4] = {0, 0, 1, -1};
int flag = 0;

void dfs(int x, int y){
    maze[x][y] = 0;
    //4近傍を探索
    for(int i=0; i < 4; i++){
            int nx = x + dx[i], ny = y + dy[i];
            if(0 <= nx and nx < h and 0 <= ny and ny < w and maze[nx][ny] != 0){
                if(nx == (xg-1) and ny == (yg-1)) {
                    flag = 1;
                    return;
                }
                dfs(nx, ny);
            }
        }
    return;
}


int main(){
    while(1){
    flag = 0;
    cin >> w >> h;
    if(w == 0 and h == 0) break;
    cin >> xs >> ys >> xg >> yg >> n;
    //ボードを初期化
    for(int i=0; i < w; i++)for(int j=0; j < h; j++) maze[i][j] = 0;
    //ボードにブロックを敷き詰める
    for(int i=0; i < n; i++){
        int c = 0, d = 0, x = 0, y = 0;
        cin >> c >> d >> x >> y;
        if(d)for(int dx=0; dx < 2; dx++)for(int dy=0; dy < 4; dy++) maze[x-1+dx][y-1+dy] = c;
        else for(int dy=0; dy < 2; dy++)for(int dx=0; dx < 4; dx++) maze[x-1+dx][y-1+dy] = c;
    }
    //迷路を単純化する
    for(int i=0; i < w; i++)for(int j=0; j < h; j++) if(maze[i][j] != maze[xs-1][ys-1]) maze[i][j] = 0;

    //search
    dfs(xs-1, ys-1);
    if(flag) cout << "OK" << endl;
    else cout << "NG" << endl;
    }
    return 0;
}