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 F[102][102];
int color,gx,gy;
bool maze;

void DFS1(int Y,int X){
    if(F[Y][X]!=color)return;
    if(Y==gy&&X==gx)maze=true;
    
    F[Y][X]=0;
    
    DFS1(Y-1,X  );
    DFS1(Y  ,X-1);
    DFS1(Y  ,X+1);
    DFS1(Y+1,X  );
}

int main(){
    int N,M,sx,sy,n;
    cin >> N >> M;
    while(N!=0&&M!=0){
        cin >> sx >> sy >> gx >> gy >> n;
        int c,d,nx,ny;
        for(int i=0;i<n;i++){
            cin >> c >> d >> nx >> ny;
            for(int y=ny;y<ny+2*(1+d);y++){
                for(int x=nx;x<nx+2*(2-d);x++){
                    F[y][x] = c;
                }
            }
        }

        color = F[sy][sx];
        maze = false;
        DFS1(sy,sx);
        cout << (maze?"OK":"NG") << endl;
        cin >> N >> M;
    }
    return 0; 
}

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

int field[101][101];
int dx[] = { 0,1,0,-1};
int dy[] = { 1,0,-1,0};
int w,h;
int xs=1,ys=2,xg,yg;
int num;

int dfs(int x, int y){

  int judge = 0,nx,ny;
  
  if(x == xg && y == yg){
    return 1;
  }

  for(int i = 0;i < 4;i++){
    nx = x + dx[i];
    ny = y + dy[i];
    if(nx <= w && ny <= h && 0 < nx && 0 < ny && field[ny][nx] == num && field[ny][nx] != -1){
      field[ny][nx] = -1;
      judge += dfs(nx,ny);
    }
  }  
  
  return judge;

}
int main(){

  int n;
  int c,d,x,y;
  int j_max,k_max;
  
  while(cin >> w >> h, w | h){
    for(int i = 0;i < 101;i++){
      for(int j = 0;j < 101;j++){
	field[i][j] = 0;
      }
    }
    cin >> xs >> ys;
    cin >> xg >> yg;
    cin >> n;
    for(int i = 0;i < n;i++){
      cin >> c >> d >> x >> y;
      if(d == 0){
	j_max = 2;
	k_max = 4;
      }else{
	j_max = 4;
	k_max = 2;
      }
      for(int j = y;j < y+j_max;j++){
	for(int k = x;k < x+k_max;k++){
	  field[j][k] = c;
	}
      }
    }
    num = field[ys][xs];
    
    if(dfs( xs, ys)){
      cout << "OK" << endl;
    }else{
      cout << "NG" << endl;
    }
  }
}

C++: //include----------------------------------------------------------------------------------------------------------------------
#include<cstdio>
#include<cmath>
#include<cstdlib>
#include<cstring>
#include<string>
#include<cctype>
#include<string>
#include<vector>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<bitset>
#include<map>
#include<algorithm>
#include<memory>


//using namespace--------------------------------------------------------------------------------------------------------------
using namespace std;

//define,const-----------------------------------------------------------------------------------------------------------------
#define rep(i, n) for(int i = 0; i < n; i++)
const int INF = 1 << 25;
#define MAX 1000

//global-----------------------------------------------------------------------------------------------------------------------
int board_range_w, board_range_h, start_x, start_y, goal_x, goal_y;
int color[MAX][MAX];
bool dp[MAX][MAX];

//function---------------------------------------------------------------------------------------------------------------------
bool solve(int x, int y){
	if ( x == goal_x && y == goal_y )
		return true;
	if ( !color[x][y] )
		return false;
	if ( color[x][y] == color[x + 1][y] )
		if ( solve(x + 1, y) )
			return true;
	if ( color[x][y] == color[x][y + 1] )
		if ( solve(x, y + 1) )
			return true;
	if ( color[x][y] == color[x][y - 1] )
		if ( solve(x, y - 1) )
			return true;
	if ( color[x][y] == color[x - 1][y] )
		if ( solve(x - 1, y) )
			return true;
	return false;
}

int main(){
	while ( scanf("%d %d", &board_range_w, &board_range_h) ) {
		if ( board_range_w == 0 && board_range_h == 0 )
			return 0;
		for ( int i = 0; i < 1000; i++ ){
			for ( int j = 0; j < 1000; j++ ){
				color[i][j] = 0;
			}
		}
		scanf("%d %d", &start_x, &start_y);
		scanf("%d %d", &goal_x, &goal_y);
		int block;
		scanf("%d", &block);
		for ( int i = 0; i < block; i++ ){
			int block_color, block_quarter, block_start_x, block_start_y;
			scanf("%d %d %d %d", &block_color, &block_quarter, &block_start_x, &block_start_y);
			color[block_start_x + 1][block_start_y + 1] = block_color;
			color[block_start_x][block_start_y + 1] = block_color;
			color[block_start_x + 1][block_start_y] = block_color;
			color[block_start_x][block_start_y] = block_color;
			if ( !block_quarter ){
				color[block_start_x + 2][block_start_y + 1] = block_color;
				color[block_start_x + 2][block_start_y] = block_color;
				color[block_start_x + 3][block_start_y + 1] = block_color;
				color[block_start_x + 3][block_start_y] = block_color;
			}										
			else{
				color[block_start_x + 1][block_start_y + 3] = block_color;
				color[block_start_x][block_start_y + 3] = block_color;
				color[block_start_x + 1][block_start_y + 2] = block_color;
				color[block_start_x][block_start_y + 2] = block_color;
			}
		}
		if ( solve(start_x, start_y) ) 
			printf("OK\n");
		else
			printf("NG\n");
	}
	return 0;
}