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<stack>
#include<string.h>
using namespace std;
struct ST {
	int a;
	int b;
	int c;
};
long long brock[1000][1000];
long long ds[1000][1000];
int q[4]={0,-1,0,1};
int p[4]={1,0,-1,0};
int main(){
	stack <ST> S;
	ST ma;
	ST ba;
	int w,h;//???????????§??????
	int xs,ys;//??????????????§?¨?
	int xg,yg;//??´????????§?¨?
	int n;//????????????????????°
	int c,d,x,y;//????????????????????±
	int i,j,m,check=0;
	while(1){
		memset(ds,0,sizeof(ds));
		memset(brock,0,sizeof(brock));
		cin>>w>>h;//???????????§????????\???
		if(w==0&&h==0){
			break;
		}
		cin>>xs>>ys>>xg>>yg;//??????????????¨??´???????????§?¨???\???
		cin>>n;//????????????????????°
		for(i=0;i<n;i++){
			cin>>c>>d>>x>>y;
			if(d==1){//???
				for(m=0;m<2;m++){
					for(j=0;j<4;j++){
						brock[x+m][y+j]=c;
					}
				}
			}
			else{//?¨?
				for(m=0;m<4;m++){
					for(j=0;j<2;j++){
						brock[x+m][y+j]=c;
					}
				}
			}
		}
		if(brock[xs][ys]!=brock[xg][yg]){
			cout<<"NG"<<endl;
		}
		else{
			ma.a=xs;
			ma.b=ys;
			ma.c=brock[xs][ys];
			ds[xs][ys]=1;
			S.push(ma);
			check=0;
			while(!S.empty()){
				ba=S.top();
				S.pop();
				ds[ba.a][ba.b]=1;
				if(ba.a==xg&&ba.b==yg){
					check=1;
					break;
				}
				if(ba.c==brock[xg][yg]){
					for(i=0;i<4;i++){
						if(ba.a+p[i]>0&&ba.a+p[i]<=w&&ba.b+q[i]>0&&ba.b+q[i]<=h&&ds[ba.a+p[i]][ba.b+q[i]]==0){
							ma.a=ba.a+p[i];
							ma.b=ba.b+q[i];
							ma.c=ba.c;
							S.push(ma);
						}
					}
				}
			}
			if(check==1){
				cout<<"OK"<<endl;
			}
			else{
				cout<<"NG"<<endl;
			}
		}
	}
	return 0;
}

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

int Board[102][102];    //Board[j, x, w][i, y, h]
bool isOK;              //迷路がOKかNGか
int xs, ys, xg, yg;     //StartとGoalの座標

void DFS(int c, int x, int y){
    if(Board[x][y] != c){
        return;
    }
    else if(x==xg && y==yg){
        isOK = true;    //Goalなら迷路はOK
        return;
    }

    Board[x][y] = 0;

    DFS(c, x+1, y  );
    DFS(c, x  , y+1);
    DFS(c, x-1, y  );
    DFS(c, x  , y-1);
}



int main(){
    int w,h;
    while(true){
        cin >> w >> h;
        if(w==0 && h==0)
            break;
        
        isOK = false;               //初期値をNGに
        for(int i=1;i<=100;i++){     //Boardの初期化
            for(int j=1;j<=100;j++)
                Board[j][i] = -1;
        } 
        cin >> xs >> ys >> xg >> yg;

        int n, c, d, x, y;
        cin >> n;
        for(int t=0;t<n;t++){
            cin >> c >> d >> x >> y;
            int wb = 2+(!d*2);      //d=0なら横長
            int hb = 2+(d*2);       //d=1なら縦長
            for(int i=0;i<hb;i++){
                for(int j=0;j<wb;j++)
                    Board[x+j][y+i] = c;
            }
        }

        DFS(Board[xs][ys], xs, ys);

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

    }

    return 0;
}

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

int board[100][100];
int xg , yg;
int w, h;
int dx[]={1,0,-1,0};
int dy[]={0,1,0,-1};
int sc;
bool b;

void dfs(int x , int y){
	if(x==xg&&y==yg) {b=true;return;}
	for(int i=0;i<4;++i){
		int tx=x+dx[i];
		int ty=y+dy[i];
		if(tx<0||ty<0||tx>=w||ty>=h) continue;
		if(board[tx][ty]!=sc|| board[tx][ty]==0) continue;
		if(b) continue;
		dfs(tx,ty);
	}
}

int main(){
	int xs , ys;
	int n;
	while(cin >> w >> h , w|h){
		b=false;
		memset(board,0,sizeof(board));
		cin >> xs >> ys >> xg >> yg >> n;
		for(int i=0;i<n;++i){
			int c , d , x , y;
			cin >> c >> d >> x >> y;
			if(d==0){
				for(int k=0;k<2;++k){
					for(int j=0;j<4;++j){
						board[x+j][y+k]=c;
					}
				}
			} else {
				for(int k=0;k<4;++k){
					for(int j=0;j<2;++j){
						board[x+j][y+k]=c;
					}
				}
			}
		}
		sc=board[xs][ys];
		int gc=board[xg][yg];
		if(sc!=gc) {}
		else dfs(xs,ys);
		cout << ( b ? "OK" : "NG") << endl;
	}
	return 0;
}

C++: #include <iostream>
#include <queue>
#include <map>

using namespace std;

typedef pair<int, int> P;

int B[101][101];

bool bfs(int w, int h, int xs, int ys, int xg, int yg);

int main(int argc, char** argv)
{
	int w, h;
	int xs, ys;
	int xg, yg;
	int n;
	int c, d, x, y;

	while( 1 )
	{
		cin >> w;
		cin >> h;
		if(w==0 && h==0) break;
		
		cin >> xs;
		cin >> ys;
		cin >> xg;
		cin >> yg;
		cin >> n;

		for(int i=0; i<n; i++)
		{
			cin >> c; cin >> d; cin >> x; cin >> y;
			if(d==0)
			{
				for(int dx=0; dx<4; dx++)
				{
					for(int dy=0; dy<2; dy++)
					{
						B[x+dx][y+dy] = c;
					}
				}
			}
			else
			{
				for(int dx=0; dx<2; dx++)
				{
					for(int dy=0; dy<4; dy++)
					{
						B[x+dx][y+dy] = c;
					}
				}
			}
		}

		cout << (bfs(w, h, xs, ys, xg, yg) ? "OK" : "NG") << endl;
	}

	return 0;
}

bool bfs(int w, int h, int xs, int ys, int xg, int yg)
{
	int x, y, c, xx, yy;
	int offset[4][2] = {{-1, 0}, {1, 0}, {0, -1}, {0, 1}};
	queue<P> q;
	P p;

	c = B[xs][ys];
	B[xs][ys] = 0;
	p.first = xs, p.second = ys;
	
	q.push(p);
	while(!q.empty())
	{
		p = q.front();
		q.pop();
		x = p.first;
		y = p.second;
		if(x==xg && y==yg) return true;
		B[x][y] = 0;

		for(int i=0; i<4; i++)
		{
			xx = x + offset[i][0];
			yy = y + offset[i][1];
			if(x>=1 && y>=1 && x<=w && y<=h)
			{
				if(B[xx][yy] == c)
				{
					p.first = xx;
					p.second = yy;
					q.push(p);
				}
			}
		}
	}

	return false;
}