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 <sstream>
#include <vector>
#include <list>
#include <string>
#include <set>
#include <map>
#include <stack>
#include <queue>
#include <algorithm>
#include <numeric>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <climits>
using namespace std;

const int size = 101;
int B[size][size];
int V[size][size];

typedef pair <int, int> PII;
typedef queue <PII> QUEUE;

int main() {
    int w, h;
    while ( cin >> w >> h && w && h ) {
        for ( int i = 0; i < h; ++ i ) {
            for ( int j = 0; j < w; ++ j ) {
                B[i][j] = 0;
                V[i][j] = 0;
            }
        }
        int xs, ys, xg, yg;
        cin >> xs >> ys >> xg >> yg;
        xs --;
        ys --;
        xg --;
        yg --;
        int n;
        cin >> n;
        for ( int i = 0; i < n; ++ i ) {
            int c, d, x, y;
            cin >> c >> d >> x >> y;
            x --;
            y --;
            for ( int j = 0; j < ( d ? 4 : 2 ); ++ j ) {
                for ( int k = 0; k < ( d ? 2 : 4 ); ++ k ) {
                    int nx = x + k;
                    int ny = y + j;
                    B[ny][nx] = c;
                }
            }
        }

//         for ( int i = 0; i < h; ++ i ) {
//             for ( int j = 0; j < w; ++ j ) {
//                 cout << B[i][j];
//             }
//             cout << endl;
//         }
//         cout << endl;

        if ( ! B[ys][xs] || ! B[yg][xg] ) {
            cout << "NG" << endl;
            continue;
        }
        
        PII start( xs, ys );
        V[ys][xs] = 1;
        QUEUE Q;
        Q.push( start );
        bool flag = true;
        while ( ! Q.empty() ) {
            PII node = Q.front();
            Q.pop();

            int x = node.first;
            int y = node.second;

            if ( x == xg && y == yg ) {
                cout << "OK" << endl;
                flag = false;
                break;
            }
            
            const int dx[4] = { 1, -1, 0, 0 };
            const int dy[4] = { 0, 0, 1, -1 };
            for ( int i = 0; i < 4; ++ i ) {
                int nx = x + dx[i];
                int ny = y + dy[i];
                if ( nx < 0 || nx >= w ) continue;
                if ( ny < 0 || ny >= h ) continue;
                if ( B[y][x] != B[ny][nx] ) continue;
                if ( V[ny][nx] ) continue;
                V[ny][nx] = 1;
                PII next( nx, ny );
                Q.push( next );
            }
        }

        if ( flag ) cout << "NG" << endl;
    }
    return 0;
}

C++: #include <cmath>
#include <ctime>
#include <algorithm>
#include <iostream>
#include <map>
#include <numeric>
#include <set>
#include <sstream>
#include <string>
#include <vector>
#include <list>
#include <deque>
#include <stack>
#include <bitset>
#include <functional>
#include <numeric>
#include <utility>
#include <iomanip>
#include <cstdio>
#include <cctype>
#include <queue>
#include <complex>
#include <climits>

typedef long long ll;

using namespace std;

int maze[110][110];
int f[110][110];
int w, h, xs, ys, xg, yg, res = 0;
int color;

void dfs(int cx, int cy){
	if(f[cx][cy]) return ;
	f[cx][cy] = 1;
	if(cx == xg && cy == yg){
		res = 1;
		return ;
	}
	for(int dx=-1; dx<=1; ++dx){
		for(int dy=-1; dy<=1; ++dy){
			if(abs(dx-dy) != 1) continue;
			int nx = cx + dx, ny = cy + dy;
			if(maze[nx][ny] == color){
				dfs(nx, ny);
			}
		}
	}
	return ;
}


int main(void){
	int n;
	while(cin >> w >> h){
		if(w == 0 && h == 0) break;
		cin >> xs >> ys >> xg >> yg >> n;
		for(int i=0; i<110; ++i){
			for(int j=0; j<110; ++j){
				maze[i][j] = 6;
				f[i][j] = 6;
			}
		}
		for(int i=1; i<=h; ++i){
			for(int j=1; j<=w; ++j){
				maze[i][j] = 0;
				f[i][j] = 0;
			}
		}

		for(int i=0; i<n; ++i){
			int c, d, x, y;
			cin >> c >> d >> x >> y;
			if(d == 0){
				for(int j=y; j<=y+1; ++j){
					for(int k=x; k<=x+3; ++k){
						maze[j][k] = c;
					}
				}
			}
			if(d == 1){
				for(int j=y; j<=y+3; ++j){
					for(int k=x; k<=x+1; ++k){
						maze[j][k] = c;
					}
				}
			}
		}

		color = maze[xs][ys];
		if(color == 0){
			cout << "NG" << endl;
			continue;
		}

		dfs(xs, ys);

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

	return 0;
}

C++: #include<iostream>
using namespace std;
int w, h, xs, ys, xg, yg, stage[101][101] = {};
int ny[4] = { 0, 1, 0, -1 }, nx[4] = { 1, 0, -1, 0 };
int bc;
bool ans = false;
void func(int x, int y){
	if (x == xg && y == yg){
		ans = true;
	}
	for (int i = 0; i < 4; i++){
		if (stage[y + ny[i]][x + nx[i]] != bc) return;
		func(x + nx[i], y + ny[i]);
	}
}
int main(){
	int n, c, d, x, y, bw, bh;
	cin >> w >> h >> xs >> ys >> xg >> yg >> n;
	for (int i = 0; i < n; i++){
		cin >> c >> d >> x >> y;
		if (d == 0){
			bw = 4;
			bh = 2;
		}
		else{
			bw = 2;
			bh = 4;
		}
		for (int j = 0; j < bh; j++){
			for (int k = 0; k < bw; k++){
				stage[y + j][x + k] = c;
			}
		}
	}
	bc = stage[1][1];
	func(1, 1);
	if (ans == true) cout << "OK\n";
	else cout << "NG\n";
	return 0;
}