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>

#define rep(i, n) for(int i = 0; i < n; ++i)
#define rep2(i, n) for(int i = 1; i <= n; ++i)
#define INF 0
#define MAX 102

using namespace std;

const int dx[] = {1, 0, -1, 0};
const int dy[] = {0, 1, 0, -1};
 
int field[102][102];
int h, w, sx, sy, gx, gy, n;
int col, dire, x, y;
int scol;

bool dfs(int nx, int ny) {
	if(nx == gx && ny == gy) return true;
	field[nx][ny] = -1;
	for(int i = 0; i < 4; ++i) {
		int nex = nx + dx[i];
		int ney = ny + dy[i];
		if(0 < nex && nex <= w && 0 < ney && ney <= h && scol == field[nex][ney]) {
			if(dfs(nex, ney)) return true;
		}
	}
	return false;
}

int main() {
	while(1) {
		scol = INF;
		cin >> h >> w;
		for(int i = 1; i <= h; ++i) {
			for(int j = 1; j <= w; ++j) {
				field[i][j] = 0;
			}
		}
		if(h == 0 && w == 0) break;
		cin >> sx >> sy >> gx >> gy;
		cin >> n;
		rep(k, n) {
			cin >> col >> dire >> x >> y;
			if(dire == 1) {
				for(int i = 0; i < 4; ++i) {
					for(int j = 0; j < 2; ++j) field[x+j][y+i] = col;
				}
			}
			else {
				for(int i = 0; i < 2; ++i) {
					for(int j = 0; j < 4; ++j) field[x+j][y+i] = col;
				}
			}
		}
		scol = field[sx][sy];
		if(dfs(sx, sy)) cout << "OK" << endl;
		else cout << "NG" << endl; 
	}
	return 0;
}

C++: #include<iostream>
#include<queue>
#define MAX 100
using namespace std;

int map[MAX+2][MAX+2];
bool check[MAX+2][MAX+2];
int dx[4] = { -1,1,0,0};
int dy[4] = { 0,0,-1,1};

int main () {

  while ( true ) {

    queue<int> next;

    while( !next.empty() ) {
      next.pop();
    }
    
    int w,h;
    cin >> w >> h ;

    if ( w == 0 )
      break;

    int xs,ys;
    cin >> xs >> ys;
    
    int xg, yg;
    cin >> xg >> yg;

    int n;
    cin >> n;

    int c,d,x,y;

    for ( int i=0; i<h+2; i++ ) {
      for ( int j=0; j<w+2; j++ ) {
	map[i][j] = 0;
	check[i][j] = true;
      }
    }

    for ( int i=0; i<n; i++ ) {
      cin >> c >> d >> x >> y;
      
      //int count = 0;
      for ( int j=0; j<2; j++ ) {
	for ( int k=0; k<4; k++ ) {
	  //cout << count;
	  if ( d == 0 ) {
	    map[y+j][x+k] = c;
	  } else {
	    map[y+k][x+j] = c;
	  }
	}
      }
      //cout << endl;
    }
    next.push(y*100 + x );

    int point;
    bool goal = false;

    int sc = map[ys][xs];
    /*
    for ( int i=0; i<h; i++ ) {
      for ( int j=0; j<w; j++ ) {
	cout << map[i+1][j+1];
      }
      cout << endl;
    }
    cout << endl;
    */
    if ( map[yg][xg] == sc ) {
	
      while ( !next.empty() ) {
	point = next.front();
	next.pop();

	check[point/100][point%100] = false;
	if (map[point/100][point%100] == 0 )
	  continue;

	if (point == yg*100+xg) {
	  if ( sc == map[yg][xg] )
	    goal = true;
	  break;
	}
	for ( int i=0; i<4; i++ ) {
	  if ( check[point/100+dy[i]][point%100+dx[i]] ) {
	    check[point/100+dy[i]][point%100+dx[i]] = false;
	    if ( map[point/100+dy[i]][point%100+dx[i]] == sc ) {
	      next.push((point/100+dy[i])*100+point%100+dx[i]);
	    }
	  }
	}
      }
    }

    if ( goal )
      cout << "OK\n";
    else
      cout << "NG\n";


  }


}

C++: #include <iostream>
using namespace std;
int n,w,h;
int M[101][101];
int a,b,c,d;

int walk(int x,int y,int color){
	if(x<1||w<x||y<1||h<y)return 0;
	if(color!=M[x][y]||color==0)return 0;
	M[x][y]=9;
	if(x==c&&y==d)return 1;
	if(walk(x+1,y,color)||
			walk(x-1,y,color)||
			walk(x,y+1,color)||
			walk(x,y-1,color))return 1;
	return 0;
}
int main(void){
	while(cin>>w>>h,w||h){
		cin>>a>>b>>c>>d;
		for(int i=1;i<=h;i++){
			for(int j=1;j<=w;j++){
				M[i][j]=0;
			}
		}
		int k;
		cin>>k;
		for(int i=0;i<k;i++){
			int w,x,y,z;
			cin>>w>>x>>y>>z;
			if(x){
				for(int Y=z;Y<z+4;Y++){
					for(int X=y;X<y+2;X++){
						M[Y][X]=w;
					}
				}
			}else{
				for(int Y=z;Y<z+2;Y++){
					for(int X=y;X<y+4;X++){
						M[Y][X]=w;
					}
				}
			}
		}
		walk(a,b,M[a][b]);
		if(M[c][d]==9)cout<<"OK"<<endl;
		else cout<<"NG"<<endl;
	}
	return 0;
}

C++: #include<iostream>
#include<cstring>
#include<stack>
using namespace std;

int w, h, xs, ys, xg, yg;
int mat[102][102];
int dx[4] = {-1, 0, 0, 1};
int dy[4] = {0, 1, -1, 0};

void init(){
    for(int i = 0; i < 102; i++){
        for(int j = 0; j < 102; j++){
            mat[i][j] = 0;
        }
    }
}

bool bfs(){
    if(mat[xs][ys] == 0 || mat[xg][yg] == 0)    return false;

    int c = mat[xs][ys];
    stack<pair<int,int>> s;
    s.push({xs,ys});
    bool visit[102][102] = {};
    
    while(!s.empty()){
        pair<int,int> now = s.top(); 
        s.pop();
        if(now.first == xg && now.second == yg){
            return true;
        }
        
        visit[now.first][now.second] = true;
        
        for(int i = 0; i < 4; i++){
            int nx = now.first + dx[i];
            int ny = now.second + dy[i];
            
            if(mat[nx][ny] == c && !visit[nx][ny]){
                s.push({nx,ny});
            }
        }
    }
    
    return false;
}


int main(){
    while(1){
        cin >> w >> h;
        if(w + h == 0)  break;
        cin >> ys >> xs >> yg >> xg;
        
        init();
        
        int n;
        cin >> n;
        
        int c, d, x, y;
        while(n-- > 0){
            cin >> c >> d >> y >> x;
            if(d == 0){
                for(int i = 0; i < 2; i++){
                    for(int j = 0; j < 4; j++){
                        mat[x+i][y+j] = c;
                    }
                }
            }else if(d == 1){
                for(int i = 0; i < 4; i++){
                    for(int j = 0; j < 2; j++){
                        mat[x+i][y+j] = c;
                    }
                }
            }
        }

        if(bfs())   cout << "OK" << endl;
        else        cout << "NG" << endl;
    }

    return 0;
}