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 <bits/stdc++.h>
using namespace std;
const int limit = 101;
int w, h, n;
int xs, ys, xg, yg;
int maze[limit][limit];
int dx[4] = {1, -1, 0, 0};
int dy[4] = {0, 0, 1, -1};
int flag = 0;
int sc;
void dfs(int x, int y){
    maze[x][y] = 0;
    //4近傍を探索
    for(int i=0; i < 4; i++){
            int nx = x + dx[i], ny = y + dy[i];
            if(0 <= nx and nx < h and 0 <= ny and ny < w and maze[nx][ny] != 0){
                if(nx == (xg-1) and ny == (yg-1)) flag = 1;
                dfs(nx, ny);
            }
        }
    return;
}


int main(){
    while(1){
    flag = 0;
    cin >> w >> h;
    if(w == 0 and h == 0) break;
    cin >> xs >> ys >> xg >> yg >> n;
    //ボードを初期化
    for(int i=0; i < w; i++)for(int j=0; j < h; j++) maze[i][j] = 0;
    //ボードにブロックを敷き詰める
    for(int i=0; i < n; i++){
        int c = 0, d = 0, x = 0, y = 0;
        cin >> c >> d >> x >> y;
        if(d)for(int dx=0; dx < 2; dx++)for(int dy=0; dy < 4; dy++) maze[x-1+dx][y-1+dy] = c;
        else for(int dy=0; dy < 2; dy++)for(int dx=0; dx < 4; dx++) maze[x-1+dx][y-1+dy] = c;
    }
    //迷路を単純化する
    for(int i=0; i < w; i++)for(int j=0; j < h; j++) if(maze[i][j] != maze[xs][ys]) maze[i][j] = 0;

    //search
    dfs(xs-1, ys-1);
    if(flag) cout << "OK" << endl;
    else cout << "NG" << endl;
    }
    return 0;
}

C++: #include<iostream>
#include<string>
#include<algorithm>
#include<list>
#include<set>
#include<map>
#include<queue>
#include<stack>
#include<numeric>
#include<vector>
#include<cstdio>
#include<climits>
#include<cfloat>
#include<cstring>
#define foreach(t,p,it) for(t::iterator it=p.begin(),it!=p.end(),++it)
#define all(p) p.begin(),p.end()
#define rep(i,n) for(int i=0;i<n;i++)
#define REP(n) rep(i,n)
using namespace std;

const int W=210,H = 210;
int block[W][H];
int ans;

int w,h,xs,ys,xg,yg,n,c,d,x,y;
void solve(int xi,int yi)
{
    if(xi==xg && yi==yg){ ans = 1; return;}
    if(block[xi][yi] == c)
    {
        block[xi][yi] = 0;
        solve(xi-1, yi);
        solve(xi, yi-1);
        solve(xi+1, yi);
        solve(xi, yi+1);
    }
    block[xi][yi] = 0;
    return;
}

int main()
{
    while(cin >> w >> h )
    {
        if(w==0 && h==0) break;
        memset(block,0,sizeof(int)*w*h);
        ans = 0;
        cin >> xs >> ys;
        cin >> xg >> yg;
        cin >> n;
        REP(n)
        {
            cin >> c >> d >> x >> y;
            //cout << x << ","<< y << endl;
            if(d==1) //tate
            {
                block[x][y] = c;
                block[x][y+1] =c;
                block[x][y+2] = c;
                block[x][y+3] = c;
                block[x+1][y] = c;
                block[x+1][y+1] = c;
                block[x+1][y+2] = c;
                block[x+1][y+3] = c;
            }
            else
            {
                block[x][y] = c;
                block[x+1][y] = c;
                block[x+2][y] = c;
                block[x+3][y] = c;
                block[x][y+1] = c;
                block[x+1][y+1] = c;
                block[x+2][y+1] = c;
                block[x+3][y+1] = c;
            }
        }
        c = block[xs][ys];
        //if(c==0) {cout <<"NG" << endl; continue;}
        
        //cout << xs << " " << ys << " " << c << endl;
        //cout <<"input " << endl;
        solve(xs,ys);

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

    }

    return 0;
}

C++: #include <iostream>
using namespace std;
int board[100][100],w,h,xg,yg;
bool f(int y,int x,int color){
	board[y][x] = -1;
	int dy[] = {-1,0,0,1},dx[] = {0,-1,1,0},i;
	if(y == yg - 1 && x == xg -1) return true;
	for(i = 0;i < 4;i++){
		if(y + dy[i] > -1 && y + dy[i] < h && x + dx[i] > -1 && x + dx[i] < w){
			if(board[y+dy[i]][x+dx[i]] == color){
				if(f(y+dy[i],x+dx[i],color)) return true;
			}
		}
	}
	return false;
}
int main(){
	int xs,ys,n,i,j,k,c,d,x,y;
	while(cin >> w >> h && (w != 0 && h != 0)){
		for(j = 0;j < 100;j++){
			for(i = 0;i < 100;i++){
				board[j][i] = -1;
			}
		}
		cin >> xs >> ys;
		cin >> xg >> yg;
		cin >> n;
		for(i = 0;i < n;i++){
			cin >> c >> d >> x >> y;
			x -= 1;
			y -= 1;
			if(d == 0){
				for(j = 0;j < 2;j++){
					for(k = 0;k < 4;k++){
						board[y+j][x+k] = c;
					}
				}
			}
			else if(d == 1){
				for(j = 0;j < 2;j++){
					for(k = 0;k < 4;k++){
						board[y+k][x+j] = c;
					}
				}
			}
		}
		if(board[ys - 1][xs - 1] != -1){
			if(f(ys - 1,xs -1,board[ys - 1][xs - 1])) cout << "OK" << endl;
			else cout << "NG" << endl;
		}
		else cout << "NG" << endl;
	}
	return 0;
}

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;

    for(int i=0;i<w;i++){
      for(int j=0;j<h;j++){
        C[i][j] = 0;
      }
    }

    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(x[i]==xs &&y[i]==ys){
        cbase = c[i];
      }

      if(d[i]==0 && c[i]==cbase){
        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 && c[i]==cbase){
        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];
          }
        }
      }
    }
    ans = 0;
    meiro(xs,ys,cbase);

    if(ans == 1){
      cout << "OK" << endl;
    }
    if(ans != 1 || C[xs][ys] == 0){
      cout << "NG" << endl;
    }
  }

  return 0;
}