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 == -1 || goal == -1) { return false; }
    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=-1, 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 = -1, goal = -1;
        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++) {
                std::cout << board[i][j] << " ";
            }
            std::cout << std::endl;
        }*/
        if (start != -1) {
            for (int i = 0; i <= h; i++) {
                for (int j = 0; j <= w; 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++: #include<iostream>
using namespace std;
#define MAX 100
static const int dx[4] = {1, 0, -1, 0};
static const int dy[4] = {0, -1, 0, 1};
int w, h, sx, sy, gx, gy, G[MAX+2][MAX+2];
bool dfs( int x, int y, int color ){
 if ( color == 0 || G[x][y] != color ) return false;
 if ( x == gx && y == gy ) return true;
 G[x][y] = 0;
 for ( int r = 0; r < 4; r++ ){
if ( dfs(x + dx[r], y + dy[r], color) ) return true;
 }
 return false;
}
main(){
 int n, c, d, px, py, ww, hh;
 while( cin >> w >> h && w ){
cin >> sx >> sy >> gx >> gy >> n;
for ( int y = 0; y < h+2; y++ )
 for ( int x = 0; x < w+2; x++ ) G[x][y] = 0;
for ( int i = 1; i <=n; i++ ){
 cin >> c >> d >> px >> py;
 if ( d == 0 ) { ww = 4; hh = 2; }
 else { ww = 2; hh = 4; }
 for ( int y = 0; y <= hh-1; y++ )
for ( int x = 0; x <= ww-1; x++ ) G[px+x][py+y] = c;
}
if ( dfs(sx, sy, G[sx][sy]) ) cout << "OK" << endl;
else cout << "NG" << endl;
 }
}

C++: #include <iostream>
using namespace std;
bool b;
int dx[]={1,0,-1,0};
int dy[]={0,1,0,-1};
void dfs(int a[][101] ,int x , int y , int w , int h , int xg , int yg , int sc){
	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(a[tx][ty]!=sc || a[tx][ty]==0) continue;
		if(b) continue;
		dfs( a,tx,ty,w,h,xg,yg,sc);
	}
}
int main(){
	int w , h;
	while(cin >> w >> h , w||h){
		int xs , ys , xg , yg ;
		int n;
		b=false;
		int board[101][101]={0};
		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){
				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;
					}
				}
			}
		}
		int sc=board[xs][ys];
		int gc=board[xg][yg];
		if(sc!=gc) {
		}
		else dfs(board , xs , ys , w , h , xg , yg , sc);
		cout << ( b ? "OK" : "NG") << endl;
	}
	return 0;
}