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[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<algorithm>
using namespace std;
int field[101][101],b[101][101],X,Y,n,dx[4]={0,1,0,-1},dy[4]={1,0,-1,0},I,sX,sY,gX,gY,ans=-1,sgc;
int func(int x,int y){
	for(I=0;I<4;I++){
		int xx=x+dx[I];
		int yy=y+dy[I];
		if(xx>0&&yy>0&&xx<=X&&yy<=Y&&field[xx][yy]==sgc&&b[xx][yy]==0){
			if(xx==gX&&yy==gY){
				if(ans==-1)ans=b[x][y];
				else ans=min(b[x][y]+1,ans);
			}
			else{
			b[xx][yy]=b[x][y]+1;
			func(xx,yy);
			}
		}
	}
	return 0;
}
int main(){
	int i,i2,c,d,x,y;
	cin>>X>>Y;
	while(X!=0){
		cin>>sX>>sY>>gX>>gY>>n;
		ans=-1;
		for(i=1;i<=100;i++){
			c=0;
			d=0;
			x=0;
			y=0;
			for(i2=1;i2<=100;i2++){
				field[i][i2]=0;
			}
		}
		for(i=1;i<=n;i++){
			cin>>c>>d>>x>>y;
			if(d==0){
				field[x][y]=c;
				field[x+1][y]=c;
				field[x+2][y]=c;
				field[x+3][y]=c;
				field[x][y+1]=c;
				field[x+1][y+1]=c;
				field[x+2][y+1]=c;
				field[x+3][y+1]=c;
			}
			else{
				field[x][y]=c;
				field[x][y+1]=c;
				field[x][y+2]=c;
				field[x][y+3]=c;
				field[x+1][y]=c;
				field[x+1][y+1]=c;
				field[x+1][y+2]=c;
				field[x+1][y+3]=c;
			}
		}
		/*for(i=1;i<=Y;i++){
			for(i2=1;i2<=X;i2++)cout<<field[i2][i];
			cout<<endl;
		}*/
		sgc=field[sX][sY];
		func(sX,sY);
		if(ans==-1)cout<<"NG"<<endl;
		else cout<<"OK"<<endl;
		cin>>X>>Y;
	}
}

C++: #include <iostream>
using namespace std;
 
int F[105][105];
int xg,yg,w,h;
 
 
void DFS(int Y,int X,int c){
  if(F[Y][X] != c || Y >w || X>h){
    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<105; i++){
      for(int j=0; j<105; 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(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 mass[102][102];
int gx,gy;
bool goal_flag;
void DFS(int x,int y,int c){
    if(mass[y][x]!=c || mass[y][x]==0)return;
    if(x==gx&&y==gy){goal_flag=true;return;}
    mass[y][x]=0;
    DFS(x+1,y,c);
    DFS(x-1,y,c);
    DFS(x,y+1,c);
    DFS(x,y-1,c);
}

int main(){
  int h,w;
  int start_x,start_y;

  int n;
  int c,d,x,y;
  while(1){
    cin>>w>>h;
    if(w==0&&h==0)break;
    cin>>start_x>>start_y;
    cin>>gx>>gy;
    cin>>n;
    for(int i=0;i<h+2;i++){
      for(int j=0;j<w+2;j++){
        mass[i][j]=0;
      }
    }

    for(int i=0;i<n;i++){
        cin>>c>>d>>x>>y;
        for(int j=0;j<2;j++){
          for(int k=0;k<4;k++){
            if(d==0){mass[y+j][x+k]=c;}
            else if(d==1){mass[y+k][x+j]=c;}
          }
        }
    }
    goal_flag=false;
    DFS(start_x,start_y,mass[start_y][start_x]);
    if(goal_flag)cout<<"OK";
    else cout<<"NG";
    cout<<endl;
  }
}