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<queue>
#define MAX 100
using namespace std;

int map[MAX+2][MAX+2];
bool check[MAX+2][MAX+2];
int dx[4] = { -1,1,0,0};
int dy[4] = { 0,0,-1,1};

int main () {

  while ( true ) {

    queue<int> next;

    while( !next.empty() ) {
      next.pop();
    }
    
    int w,h;
    cin >> w >> h ;

    if ( w == 0 )
      break;

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

    int n;
    cin >> n;

    int c,d,x,y;

    for ( int i=0; i<MAX+2; i++ ) {
      for ( int j=0; j<MAX+2; j++ ) {
	map[i][j] = 0;
	check[i][j] = true;
      }
    }

    for ( int i=0; i<n; i++ ) {
      cin >> c >> d >> x >> y;
      
      //int count = 0;
      for ( int j=0; j<2; j++ ) {
	for ( int k=0; k<4; k++ ) {
	  //cout << count;
	  if ( d == 0 ) {
	    map[y+j][x+k] = c;
	  } else {
	    map[y+k][x+j] = c;
	  }
	}
      }
      //cout << endl;
    }

    next.push(y*1000 + x );

    int point;
    bool goal = false;

    int sc = map[ys][xs];

    /*
    for ( int i=0; i<=h; i++ ) {
      for ( int j=0; j<=w; j++ ) {
	cout << map[i+1][j+1];
      }
      cout << endl;
    }
    cout << endl;
    */
    int xn,yn;
    if ( map[yg][xg] == sc ) {
      if ( sc == 0 || map[yg][xg] ) {
      while ( !next.empty() ) {
	point = next.front();
	next.pop();
	xn = point%1000;
	yn = point/1000;

	if (map[yn][xn] == 0 )
	  continue;

	if (point == yg*1000+xg) {
	  goal = true;
	  break;
	}

	for ( int i=0; i<4; i++ ) {
	  if ( check[yn+dy[i]][xn+dx[i]] ) {
	    check[yn+dy[i]][xn+dx[i]] = false;
	    if ( map[yn+dy[i]][xn+dx[i]] == sc ) {
	      next.push((yn+dy[i])*1000+ xn +dx[i]);
	    }
	  }
	}
      }
      }
    }

    if ( goal )
      cout << "OK\n";
    else
      cout << "NG\n";
  }
}

C++: #include<cstdio>
#include<iostream>
#include<algorithm>
#include<cstring>
#include<string>
#include<queue>
using namespace std;
int field[128][128];
bool memo[128][128];
int dx[] = {-1,0,0,1},dy[] = {0,-1,1,0};
int w,h;
void func(int x,int y,int c){
	if(memo[y][x])return ;
	if(field[y][x] != c)return ;
	memo[y][x] = 1;
	for(int i = 0; i < 4; i++){
		func(x+dx[i],y+dy[i],c);
	}
	return ;
}
int main(){
	while(scanf("%d%d",&w,&h),w,h){
		int xs,ys,xg,yg,n;
		memset(field,0,sizeof(field));
		memset(memo,0,sizeof(memo));
		scanf("%d%d%d%d%d",&xs,&ys,&xg,&yg,&n);
		for(int i = 0; i < n; i++){
			int c,d,x,y;
			scanf("%d%d%d%d",&c,&d,&x,&y);
			if(d == 0){
				for(int j = x; j < x + 4; j++){
					field[y][j] = c;
					field[y+1][j] = c;
				}
			}
			else{
				for(int j = y; j < y + 4; j++){
					field[j][x] = c;
					field[j][x+1] = c;
				}
			}
		}
		func(xs,ys,field[ys][xs]);
		cout << (memo[yg][xg]==1?"OK":"NG") << endl;
	}
	return 0;
}

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

int map[102][102];

void route(int w, int h, int color) {
	if (map[w][h] != color)
		return;
	map[w][h] = 10;
	route(w, h + 1, color);
	route(w + 1, h, color);
	route(w, h - 1, color);
	route(w - 1, h, color);
}


int main() {
	int h, w, xs, ys, xg, yg, n;
	int c, d, x, y,color;

	while (1) {
		cin >> w >> h;		
		if (w == 0 && h == 0)
			break;

		cin>>xs >> ys >> xg >> yg >> n;

		for (int i = 0; i<n; i++) {
			cin >> c >> d >> x >> y;
			if (d == 0) {
				for (int j = 0; j < 4; j++)
					map[j + x][y] = map[j + x][y + 1] = c;
			}
			else {
				for (int j = 0; j < 4; j++)
					map[x][y + j] = map[x + 1][y + j] = c;
			}
		}

		color = map[xs][ys];
		route(xs, ys, color);
		
		if (map[xg][yg]==10)
			cout << "OK" << endl;
		else
			cout << "NG"<<endl;
	}

	return 0;
}

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



typedef vector<vector<int> > Matrix;
int w,h,xs,ys,xg,yg,n,flag;

class Block{
public:
  int color;
  int direction;
  int x,y,dx,dy;
  void write(Matrix &board){
    if(direction == 0)
      dx = 4,dy = 2;
    else if(direction == 1)
      dx = 2,dy = 4;
    for(int i=0; i<dx; ++i){
      for(int j=0; j<dy; ++j){
	(board.at(x+i-1)).at(y+j-1) = color;
      }
    }
  }
};
  
void func(Matrix &board,int nx,int ny){
  if( nx==xg && ny==yg) flag = 1;
  else if( w<=nx+1 || h<=ny+1) return;
  if(board[nx-1][ny-1]==board[nx][ny-1])
    func(board,nx+1,ny);
  if(board[nx-1][ny-1]==board[nx-1][ny])
    func(board,nx,ny+1);
}


int main(void){
  string res;
  while(1){
    cin >> w >> h;
    if( w==0 && h==0) return 0;
    cin >> xs >> ys >> xg >> yg >> n;
    Block *object;
    object = new Block[n];
    Matrix board(w, vector<int>(h,0));
    for(int i=0; i<n; ++i){
      cin >> object[i].color;
      cin >> object[i].direction;
      cin >> object[i].x;
      cin >> object[i].y;
      object[i].write(board);
    }
    func(board,xs,ys);
    if(flag==1) res = "OK";
    else res = "NG";
    cout << res << endl;
    flag = 0;
    delete[] object;
    board.clear();
  }
}