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 <vector>
#include <string>
#include <cmath>
#include <set>
#include <algorithm>
#include <array>
#include <complex>
#include <utility>
#include <map>
int needleX[4] = { -1,0,1,0 };
int needleY[4] = { 0,1,0,-1 };
bool dfs(int start,int goal,int x, int y, int goalx, int goaly, std::vector<std::vector<bool>>&canGo) {
    if (x == goalx && y == goaly) { return true; }
    if (start != goal) {
        return false;
    }
    canGo[y][x] = false;
    for (int i = 0; i < 4; i++) {
        int next_x = x + needleX[i];
        int next_y = y + needleY[i];

        if (canGo[next_y][next_x]) {
            bool flag = dfs(start, goal,next_x, next_y, goalx, goaly, canGo);
            if (flag)
                return true;
        }
    }
    return false;
}
int main(void) {
    int h, w, n;
    std::cin >> w >> h;
    std::vector<std::string> ans;
    while(h!=0&& w!=0){
        int color, orient, leftX, leftY;
        int sx, sy, gx, gy;
        std::cin >> sx >> sy >> gx >> gy;
        std::vector<std::vector<int>> board(h + 2, std::vector<int>(w+ 2, 0));
        std::vector<std::vector<bool>> canGo(h + 2, std::vector<bool>(w + 2, false));
        std::cin >> n;
        int start = 0, goal = 0;
        for (int i = 0; i < n; i++) {
            std::cin >> color >> orient >> leftX >> leftY;


            if (orient == 0) {
                for (int j = 0; j <= 3; j++) {
                    for (int k = 0; k <= 1; k++) {
                        board[leftY + k][leftX + j] = color;
                        if (leftX + j == sx && leftY + k == sy) {
                            start = color;
                        }
                        else if (leftX + j == gx && leftY + k == gy) {
                            goal = color;
                        }
                    }
                }

            }
            else {
                for (int j = 0; j <= 1; j++) {
                    for (int k = 0; k <= 3; k++) {
                        board[leftY + k][leftX + j] = color;
                        if (leftX + j == sx && leftY + k == sy) {
                            start = color;
                        }
                        else if (leftX + j == gx && leftY + k == gy) {
                            goal = color;
                        }
                    }
                }
            }
        }
        
        for (int i = 0; i <= w; i++) {
            for (int j = 0; j <= h; j++) {
                if (board[i][j] == start) {
                    canGo[i][j] = true;
                }
            }
        }
        bool result = dfs(start,goal,sx, sy, gx, gy, canGo);
        if (result) { ans.push_back("OK"); }
        else { ans.push_back("NG"); }
        std::cin >> h >> w;
    }
    int anssize = ans.size();
    for (int i = 0; i < anssize; i++) {
        std::cout << ans[i] << std::endl;
    }
    return 0;
}

C++: #define _USE_MATH_DEFINES
#include<cstdio>
#include<iostream>
#include<vector>
#include<algorithm>
#include<queue>
#include<stack>
#include<cmath>
#include<climits>
#include<map>
#include<string>
using namespace std;

const int dy[4] = {-1, 0, 1, 0}, dx[4] = {0, 1, 0, -1};

struct Data{
	int y, x;
	Data(){}
	Data(int _y, int _x){
		y = _y; x = _x;
	}
};

int fld[100][100];

void PaintFld(int c, int x, int y, int w, int h){
	for(int i = 0; i < h; i++){
		for(int j = 0; j < w; j++){
			fld[y + i][x + j] = c;
		}
	}
}

int main(){
	int W, H;
	while(cin >> W >> H, W || H){
		int Xs, Ys, Xg, Yg, N, C, D, X, Y;
		cin >> Xs >> Ys >> Xg >> Yg >> N;
		Xs--; Ys--; Xg--; Yg--;
		for(int i = 0; i < N; i++){
			cin >> C >> D >> X >> Y;
			X--; Y--;
			if(D == 0) PaintFld(C, X, Y, 4, 2);
			else PaintFld(C, X, Y, 2, 4);
		}

		queue<Data> q;
		Data q_front;
		bool memo[100][100] = {}, ans = false;
		q.push( Data(Xs, Ys) );
		while( !q.empty() ){
			q_front = q.front(); q.pop();

			if(q_front.y == Yg && q_front.x == Xg){
				ans = true; break;
			}

			if(memo[q_front.y][q_front.x]) continue;
			memo[q_front.y][q_front.x] = true;

			for(int i = 0; i < 4; i++){
				int ny = q_front.y + dy[i];
				int nx = q_front.x + dx[i];

				if(ny < 0 || H <= ny || nx < 0 || W <= nx || fld[ny][nx] != fld[Ys][Xs])
					continue;
				q.push( Data(ny, nx) );
			}
		}

		if(ans) puts("OK");
		else puts("NG");
	}
	return 0;
}

C++: #include <cstdio>
#include <cstring>
int board[100][100];
bool vst[100][100];
int dx[]={1,0,-1,0},dy[]={0,1,0,-1};
int w,h,xs,ys,xg,yg,n;
bool dfs(int x,int y) {
	if(x==xg && y==yg)
		return true;
	vst[x][y]=true;
	for(int i=0;i<4;i++) {
		int nx=x+dx[i],ny=y+dy[i];
		if(0>nx||nx>=w||0>ny||ny>=h)
			continue;
		if(board[nx][ny]!=board[xs][ys])
			continue;
		if(vst[nx][ny])
			continue;
		if(dfs(nx,ny)) return true;
	}
	return false;
}
int main() {
	while(scanf("%d %d",&w,&h),w|h) {
		scanf("%d %d",&xs,&ys); xs--;ys--;
		scanf("%d %d",&xg,&yg); xg--;yg--;
		scanf("%d",&n);
		memset(board,0,sizeof(board));
		memset(board,0,sizeof(vst));
		for(int i=0;i<n;i++) {
			int c,d,x,y;
			scanf("%d %d %d %d",&c,&d,&x,&y); x--;y--;
			if(d==0) {
				for(int i=0;i<4;i++) for(int j=0;j<2;j++)
					board[x+i][y+j]=c;
			}else {
				for(int i=0;i<2;i++) for(int j=0;j<4;j++)
					board[x+i][y+j]=c;
			}
		}
		printf("%s\n",dfs(xs,ys)?"OK":"NG");
	}
}