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 <cstdio>
#include <iomanip>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <bitset>
#include <stack>
#include <utility>
#include <numeric>
#include <algorithm>
#include <functional>
#include <cctype>
#include <complex>
#include <string>
#include <sstream>

using namespace std;

#define all(c) c.begin(),c.end()
#define rall(c) c.rbegin(),c.rend()
#define mp(a,b) make_pair((a),(b))
#define eq ==

typedef long long ll;
typedef complex<double> point;
typedef pair<int,int> pii;

// →↑←↓
const int dx[] = {1,0,-1,0};
const int dy[] = {0,-1,0,1};


const double EPS = 1e-9;

int main(){

    while(true){
        int w,h;
        cin >> w >> h;
        if(w == 0) break;
        int sy,sx,gy,gx;
        cin >> sx >> sy >> gx >> gy;
        sx--,sy--,gx--,gy--;
        int n;
        cin >> n;
        vector<vector<int> > color(h,vector<int>(w));
        for(int block=0;block<n;block++){
            int c,d,x,y;
            cin >> c >> d >> x >> y;
            x--;y--;
            // yoko
            if(d == 0){
                for(int i=0;i<2;i++){
                    for(int j=0;j<4;j++){
                        color[y+i][x+j] = c;
                    }
                }
            }else{
                for(int i=0;i<4;i++){
                    for(int j=0;j<2;j++){
                        color[y+i][x+j] = c;
                    }
                }
            }
        }
        // for(int i=0;i<h;i++){
        //     for(int j=0;j<w;j++){
        //         cerr << color[i][j];
        //     }
        //     cerr << endl;
        // }
        int c = color[sy][sx];
        vector<vector<char> > visited(h,vector<char>(w));
        queue<pair<int,int> > Q;
        Q.push(make_pair(sy,sx));
        while(not Q.empty()){
            int y = Q.front().first;
            int x = Q.front().second;
            Q.pop();

            if(y >= h or y < 0 or x >= w or x < 0) continue;
            if(color[y][x] != c) continue;
            if(visited[y][x]) continue;
            visited[y][x] = true;
            for(int i=0;i<4;i++){
                Q.push(make_pair(y+dy[i],x+dx[i]));
            }
        }
        if(visited[gy][gx]){
            cout << "OK" << endl;
        }else{
            cout << "NG" << endl;
        }
    }
    return 0;
}

C++: #include<iostream>
#include<string>
#include<vector>
#include<utility>
#include<queue>
#include<algorithm>
#include<cmath>
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<complex>
#define INF 2147483647
#define llINF 9223372036854775807
#define pb push_back
#define mp make_pair 
#define F first
#define S second
#define ll long long

using namespace std;
int main(){
  int w,h;
  while(cin>>w>>h,w+h){
    int xs,ys,xg,yg;
    bool Map[h+10][w+10]={};
    bool flag=false;
    cin>>xs>>ys>>xg>>yg;
    xs--;ys--;xg--;yg--;
    int n;cin>>n;
    int Map2[h+10][w+10]={};
    Map[ys][xs]=true;
    queue<pair<int,int> >que;
    que.push(mp(ys,xs));
    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=y;i<y+2;i++)
	  for(int j=x;j<x+4;j++)
	    Map2[i][j]=c;
      }else if(d==1){
	for(int i=y;i<y+4;i++)
	  for(int j=x;j<x+2;j++)
	    Map2[i][j]=c;
      }
    }
    for(int i=0;i<h;i++){
      for(int j=0;j<w;j++)
	cout<<Map2[i][j]<<" ";
      cout<<endl;
    }
    int vx[8]={0,-1,0,1,1,1,-1,-1};
    int vy[8]={1,0,-1,0,-1,1,-1,1};
    while(!que.empty()){
      pair<int,int>now=que.front();
      que.pop();
      if(now.F==xg&&now.S==yg){
	flag=true;
	break;
      }
      for(int kk=0;kk<8;kk++){
	int as=now.F+vx[kk];int bs=now.S+vy[kk];
	if(as<h&&as>=0&&bs<w&&bs>=0&&Map2[now.F][now.S]==Map2[as][bs]&&!Map[as][bs]){
	  que.push(mp(as,bs));
	  Map[as][bs]=true;
	}
      }
    }
    if(flag)
      cout<<"OK"<<endl;
    else
      cout<<"NG"<<endl;
  }
  return 0;
}

C++: #include <cstdio>
#include <cstring>

using namespace std;

int map[128][128];
int sx, sy, gx, gy;
int sc;

int dx[] = {0, 1, 0, -1};
int dy[] = {1, 0, -1, 0};

bool dfs(int ty, int tx)
{
	if (ty == gy && tx == gx){
		return (true);
	}
	
	map[ty][tx] = -1;
	
	for (int i = 0; i < 4; i++){
		if (map[ty + dy[i]][tx + dx[i]] == sc){
			if (dfs(ty + dy[i], tx + dx[i]) == true){
				return (true);
			}
		}
	}
	
	return (false);
}

int main()
{
	int w, h;
	int n;
	
	while (scanf("%d %d", &w, &h) && w){
		memset(map, -1, sizeof(map));
		scanf("%d %d", &sx, &sy);
		scanf("%d %d", &gx, &gy);
		scanf("%d", &n);
		
		for (int i = 0; i < n; i++){
			int col, dir, tx, ty;
			scanf("%d %d %d %d", &col, &dir, &tx, &ty);
			if (dir == 0){
				for (int dy = 0; dy < 2; dy++){
					for (int dx = 0; dx < 4; dx++){
						map[ty + dy][tx + dx] = col;
					}
				}
			}
			else {
				for (int dy = 0; dy < 4; dy++){
					for (int dx = 0; dx < 2; dx++){
						map[ty + dy][tx + dx] = col;
					}
				}
			}
		}
		sc = map[sy][sx];
		printf("%s\n", ~sc && dfs(sy, sx) == true ? "OK" : "NG");
	}
	
	return (0);
}