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<algorithm>
#include<cstring>
using namespace std;

int xs,ys,c,a[105][105],memo[105][105],ans,p,w,h;

int solve(int yg,int xg){

  a[yg][xg] = 0;

  if(xs == xg && ys == yg) return ans = 1;

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

int main(){
  int xg,yg,n,d,x,y;

  while(true){
    cin >> w >> h;
    if(!w && !h) break;

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

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

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

      if(d == 0){
	for(int i=y;i<y+2;i++){
	  for(int j=x;j<x+4;j++) a[i][j] = c;
	}
      }

      else if(d == 1){
	for(int i=y;i<y+4;i++){
	  for(int j=x;j<x+2;j++) a[i][j] = c;
	}
      }
    }

    p = a[yg][xg];
    solve(yg,xg);

    if(ans == 1)   cout << "OK" << endl;
    else if(ans == 0)cout << "NG" << endl;

  }
}

C++: #include <iostream>
using namespace std;
  
int F[105][105];
int xg,yg;
  
  
void DFS(int Y,int X,int c){
  if(F[Y][X] != c){
    return;
  }
  
  F[Y][X] = -2000;
  DFS(Y-1,X  ,c);
  DFS(Y  ,X+1,c);
  DFS(Y+1,X  ,c);
  DFS(Y  ,X-1,c);
}
  
  
int main(){
  int w,h,xs,ys,n;
  while(1){
    cin >> w >> h;
    if(w == 0 && h == 0)
      break;

      
    cin >> xs >> ys >> xg >> yg >> n;
    int c[n],d[n],x[n],y[n],ca;
    for(int i=0;i<n;i++){
      cin >> c[i] >> d[i] >> x[i] >> y[i];
    }
    for(int i=0;i<n;i++){
      if(c[i] == 0)
        ca = 10;
      else if(i == n-1)
        c = 0;
    }
    for(int i=0; i<102; i++){
          for(int j=0; j<102; j++){
            F[i][j]=ca;
          }
    }
    for(int i=0;i<n;i++){
      if(d[i] == 0){
        for(int j=0;j<4;j++){
          F[x[i]+j][y[i]] = c[i];
          F[x[i]+j][y[i]+1] = c[i];
        }
      } else {
        for(int j=0;j<4;j++){
          F[x[i]][y[i]+j] = c[i];
          F[x[i]+1][y[i]+j] = c[i];
        }
      }
    }
 
  DFS(xs,ys,F[xs][ys]);
  
  if(F[xg][yg] == -2000){
    cout << "OK" << endl;
  } else {
    cout << "NG" <<endl;
  }
  }
}

C++: #include <iostream>
using namespace std;
 
int C[102][102];
int ans;
int xg,yg;
 
void meiro(int W,int H,int c){
 if(W==xg && H==yg){
   ans = 1;
   return;
 }
 
 if(C[W][H]!=c){
   return;
 }
 
 C[W][H] = '.';
 
 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;
   }
 
   int xs,ys;
   cin >> xs >> ys;
 
   cin >> xg >> yg;
 
   int n;
   cin >> n;
   int c[n],d[n],x[n],y[n];
 
   int cbase;
 
   for(int i=0;i<n;i++){
     cin >> c[i] >> d[i] >> x[i] >> y[i];
 
     if(d[i]==0){
       for(int j=x[i];j<x[i]+4;j++){
         for(int k=y[i];k<y[i]+2;k++){
           C[j][k]=c[i];
         }
       }
     }
     if(d[i]==1){
       for(int j=x[i];j<x[i]+2;j++){
         for(int k=y[i];k<y[i]+4;k++){
           C[j][k]=c[i];
         }
       }
     }
 
     if(x[i]==1 &&y[i]==1){
       cbase = c[i];
     }
   }
   ans = 0;
if(cbase == 0){
 cout << "NG"<<endl;
 continue;
}
   meiro(xs,ys,cbase);
 
   if(ans==1){
     cout << "OK" << endl;
   }else{
     cout << "NG" << endl;
   }
 }
 
 return 0;
}

C++: #include<iostream>
#include<cstring>
#include<queue>
#include<map>
using namespace std;
int C,goal,n,x,y,xs,ys,xg,yg,mas[110][110]={{0}};
int dx[4]={1,0,-1,0};
int dy[4]={0,1,0,-1};
int d[110][110];
typedef pair<int,int>P;

int bfs();
int main(){

  while(1){
    goal=0;
    memset(mas,0,sizeof(mas));
    //memset(d,0,sizeof(d));
    C = goal = n = x = y = xs = ys = xg = yg = 0;

    cin >> x >> y;//ボードの大きさ。 ※：x=横。y=縦。
    if(x==0 && y==0){
      break;
    }
    cin >> xs >> ys;//スタート地点。
    cin >> xg >> yg;//ゴール地点。
    cin >> n;//ブロックの数。
    
    //色染め。
    int color,dire,xx,yy;
    for(int t=0;t<n;t++){
      cin >> color >> dire >> xx >> yy;

      //横長。
      if(dire==0){
	for(int i=0;i<2;i++){
	  for(int j=0;j<4;j++){
	    mas[yy+i][xx+j]=color;
	  }
	}
      }
      
      //縦長。
      else{
	for(int i=0;i<4;i++){
	  for(int j=0;j<2;j++){
	    mas[yy+i][xx+j]=color;
	  }
	}
      }
      
    }
    
    //通る色　摘出。
    C=mas[ys][xs];
    //cout << "color:" << C << endl;
    
    if(C!=0 && mas[ys][xs]==mas[yg][xg]){

      bfs();

    
      if(goal==1){
	cout << "OK" << endl;
	goal=0;
      }
      else{
	cout << "NG" << endl;
      }
    }
    else{
      cout << "NG" << endl;
    }
  }
}

int bfs(){
  queue<P>que;
  memset(d,-1,sizeof(d));
  que.push(P(ys,xs));
  d[ys][xs]=0;
  while(!que.empty()){
    P p=que.front();
    que.pop();
    if(p.first==yg && p.second==xg){
      goal=1;
      break;
    }
    for(int i=0;i<4;i++){
      int ny=p.first+dy[i];
      int nx=p.second+dx[i];
      if(ny>=1 && ny<=y && nx>=1 && nx<=x && mas[ny][nx]==C && d[ny][nx]==-1){
	d[ny][nx] = 1;
	que.push(P(ny,nx));
      }
    }
  }
  return (0);
}