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 dr direction
#define cl color
#define fi first
#define se second

using namespace std;
typedef pair<int, int> pii;

class Block{
public:
    int color;// 1~5
    int direction;// 0:-, 1:|
    int x, y;
    void init(int c, int d, int xx, int yy);
};

void Block::init(int c, int d, int xx, int yy){
    color=c;
    direction=d;
    x=xx;
    y=yy;
}

int w, h, xs, ys, xg, yg, n;
int fld[100][100], dis[100][100];
const pii dxdy[]={{1, 0}, {-1, 0}, {0, 1}, {0, -1}};
const int inf=1e8;

string solve(){// bfs
    queue<pii> qu;
    qu.push(make_pair(ys, xs));
    int C=fld[ys][xs];
    fill(dis[0], dis[100], inf);
    dis[ys][xs]=0;

    if(C==0) return "NO";
    while(!qu.empty()){
        pii now=qu.front(); qu.pop();
        if(now.fi==yg&&now.se==xg){
            return "OK";
        }

        for(int k=0; k<4; k++){
            pii nx=make_pair(now.fi+dxdy[k].fi, now.se+dxdy[k].se);
            if(!(0<=nx.fi&&nx.fi<h&&0<=nx.se&&nx.se<w)) continue;
            if(fld[nx.fi][nx.se]!=C) continue;
            if(dis[nx.fi][nx.se]!=inf) continue;

            dis[nx.fi][nx.se]=dis[now.fi][now.se]+1;
            qu.push(nx);
        }
    }

    return "NO";
}

int main(){

    while(1){
        cin>> w>> h;
        if(w==0&&h==0) break;
        cin>> xs>> ys>> xg>> yg>> n;
        xs--; ys--; xg--; yg--;
        Block block[n];
        for(int i=0; i<n; i++){
            int c, d, xx, yy;
            cin>> c>> d>> xx>> yy;
            xx--; yy--;
            block[i].init(c, d, xx, yy);
        }

        // make field
        fill(fld[0], fld[100], 0);
        for(int k=0; k<n; k++){
            int X=block[k].x, Y=block[k].y;
            if(block[k].dr==0){
                for(int i=0; i<2; i++){
                    for(int j=0; j<4; j++){
                        fld[Y+i][X+j]=block[k].cl;
                    }
                }
            }else{
                for(int i=0; i<4; i++){
                    for(int j=0; j<2; j++){
                        fld[Y+i][X+j]=block[k].cl;
                    }
                }
            }
        }
/*
        for(int i=0; i<w; i++){
            for(int j=0; j<h; j++){
                cout<< fld[i][j]<<" ";
            }
            cout<< endl;
        }
//*/
        cout<< solve()<< endl;
    }

    return 0;
}

C++: #include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};

bool dfs(int y, int x, int c, int gy, int gx, vector<vector<int> > &field){
    if(field[y][x] != c) return false;
    if(y==gy && x==gx) return true;
    field[y][x] = 0;
    for(int i=0; i<4; i++){
        if(dfs(y+dy[i], x+dx[i], c, gy, gx, field)) return true;
    }
    return false;
}

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

        int sx,sy, gx,gy, n;
        cin >> sx >> sy >> gx >> gy >> n;
        vector<vector<int> > b(h+2, vector<int>(w+2, 0));
        for(int i=0; i<n; i++){
            int c,d,x,y;
            cin >> c >> d >> x >> y;
            for(int r=0; r<2; r++){
                b[y][x] = b[y+1][x] = b[y][x+1] = b[y+1][x+1] = c;
                if(d == 0){
                    x += 2;
                }else{
                    y += 2;
                }
            }
        }

        if(b[sy][sx] == 0 || !dfs(sy, sx, b[sy][sx], gy, gx, b)){
            cout << "NG" << endl;
        }else{
            cout << "OK" << endl;
        }
    }
    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
const int limit = 100;
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;

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;
}