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 w, h;
int xg, yg;
int data[100][100];
int dx[]={0, 1, 0, -1};
int dy[]={-1, 0, 1, 0};
bool visited[100][100];
bool dfs(int, int, int);

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

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

    cin >> n;
    for(int i=0;i<h;i++){
      for(int j=0;j<w;j++){
	data[i][j]=0;
      }
    }
    for(int i=0;i<n;i++){
      int c, d, x, y;
      cin >> c >> d >> x >> y;
      x--;
      y--;
      if(d==0){
	for(int i=0;i<2;i++){
	  for(int j=0;j<4;j++){
	    data[i+y][j+x]=c;
	  }
	}
      }else{
	for(int i=0;i<4;i++){
	  for(int j=0;j<4;j++){
	    data[i+y][j+x]=c;
	  }
	}
      }
    }
    for(int i=0;i<h;i++){
      for(int j=0;j<w;j++){
	visited[i][j]=false;
      }
    }

    if(dfs(ys, xs, data[ys][xs])){
      cout << "OK" << endl;
    }else{
      cout << "NG" << endl;
    }
  }
  return 0;
}

bool dfs(int y, int x, int c){
  if(y==yg && x==xg){
    return true;
  }
  visited[y][x]=true;
  bool ans=false;
  for(int i=0;i<4;i++){
    int ty=y+dy[i];
    int tx=x+dx[i];
    if(ty>=0 && ty<h){
      if(tx>=0 && tx<w){
	if(data[ty][tx]==c && !visited[ty][tx]){
	  ans=dfs(ty, tx, c);
	  if(ans) break;
	}
      }
    }
  }
  return ans;
}

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

int F[101][102];

void DFS(int Y, int X, int c) {
        //cout << Y << " " << X << endl;
        if (F[Y][X] != c || F[Y][X] == 0)
                return;
        F[Y][X] = 10;
        DFS(Y - 1, X, c);//???
                                                 //DFS(Y - 1, X+1, A_ito);//??????
        DFS(Y, X + 1, c);//???
                                                 //DFS(Y + 1, X+1, A_ito);//??????
        DFS(Y + 1, X, c);//???
                                                 //DFS(Y + 1, X-1, A_ito);//??????
        DFS(Y, X - 1, c);//???
                                                 //DFS(Y - 1, X-1, A_ito);//??????
}


int main()
{
        int xs, ys, xg, yg, n;
        int c, d, x, y;
        int W = 0, H = 0;

        while (!(W == H == 0)) {
                cin >> W >> H;
                cin >> xs >> ys >> xg >> yg >> n;
                for (int i = 1;i <= n;i++) {
                        cin >> c >> d >> x >> y;
                        if (d == 0) {
                                F[x][y] = c;
                                F[x][y + 1] = c;
                                F[x + 1][y] = c;
                                F[x + 1][y + 1] = c;
                                F[x + 2][y] = c;
                                F[x + 2][y + 1] = c;
                                F[x + 3][y] = c;
                                F[x + 3][y + 1] = c;
                        }
                        if (d == 1) {
                                F[x][y] = c;
                                F[x + 1][y] = c;
                                F[x][y + 1] = c;
                                F[x + 1][y + 1] = c;
                                F[x][y + 2] = c;
                                F[x + 1][y + 2] = c;
                                F[x][y + 3] = c;
                                F[x + 1][y + 3] = c;
                        }
                }
                DFS(ys, xs, F[ys][xs]);

                if (F[yg][xg] == 10) {
                        cout << "OK" << endl;
                }
                else { cout << "NG"<<endl; }
                for (int i = 0;i < H;i++) {
                        for (int j = 0;j < W;j++) {
                                F[i][j] = 0;
                        }
                }
        }

        return 0;
}

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

bool dfs(int x,int y);
int w,h;
int xs,ys;
int xg,yg;
int board[111][111];
int cheak[111][111];
int xd[]={0,-1,0,1};
int yd[]={-1,0,1,0};
int main(){
  int n;
  int c,d,x,y;
  int a[]={1,0,1,0,1,0,1};
  int b[]={0,1,1,2,2,3,3};
  while(1){
    cin >> w >> h;
    if(w==0 && h==0) break;
    for(int i=0;i<h;i++){
      for(int j=0;j<w;j++){
	board[i][j]=0;
	cheak[i][j]=0;
      }
    }
    cin >> xs >> ys;
    cin >> xg >> yg;
    cin >> n;
    for(int i=0;i<n;i++){
      cin >> c >> d >> x >> y;
      board[y-1][x-1]=c;
      for(int j=0;j<7;j++){
	if(d==0) board[y+a[j]-1][x+b[j]-1]=c;
	else board[y+b[j]-1][x+a[j]-1]=c;
      }
    }
    if(board[ys][xs]!=0){
      if(dfs(xs-1,ys-1)==true) cout << "OK" << endl;
      else cout << "NG" << endl;
    }
    else cout << "NG" << endl;
  }
}

bool dfs(int x,int y){
  cheak[y][x]=1;
  if(x==xg-1 && y==yg-1) return true;
  for(int i=0;i<4;i++){
    int xn=x+xd[i];
    int yn=y+yd[i];
    if(xn>=0 && xn<w && yn>=0 && yn<h && board[yn][xn]==board[ys-1][xs-1] && cheak[yn][xn]==0){
      if(dfs(xn,yn)==true) return true;
    }
  }
  return false;
}