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 <cstdio>
using namespace std;
typedef long long ll;
#define rep(i,n) for(int i=0;i<(n);i++)
int dy[] = {1, 0, 0, -1};
int dx[] = {0, 1, -1, 0};
int b[110][110];
int w, h;
int xs, ys, xg, yg;
int color;
bool flag = false;
bool used[110][110];

void dfs(int y, int x, int py, int px){
	rep(i, 4){
		int ny = y + dy[i], nx = x + dx[i];
		if(used[ny][nx]) continue;//???????????¨???????????????????????????
		if(!(0 <= ny && ny < h && 0 <= nx && nx < w)) continue;
		if(b[ny][nx] != color) continue;
		if(ny == py && nx == px) continue;
		if(ny == yg && nx == xg){
			used[ny][nx] = true;
			flag = true; return;//????????????
		}
		used[ny][nx] = true;
		dfs(ny, nx, y, x);
	}
	return;//????????¢?????¨???????????????
}

int main(void){
	while(1){
		rep(i, 110)rep(j, 110){
			b[i][j] = -1; used[i][j] = false;
		}
		cin >> w >> h;
		if(w == 0 && h == 0) return 0;
		cin >> xs >> ys >> xg >> yg;
		xs--; ys--; xg--; yg--;
		int n; cin >> n;
		rep(i, n){
			int c, d, x, y;
			cin >> c >> d >> x >> y;
			x--; y--;
			if(d == 0){//?¨?
				b[y][x] = b[y][x + 1] = b[y][x + 2] = b[y][x + 3] = c;
				b[y + 1][x] = b[y + 1][x + 1] = b[y + 1][x + 2] = b[y + 1][x + 3] = c;
			}else{//???
				b[y][x] = b[y][x + 1] = c;
				b[y + 1][x] = b[y + 1][x + 1] = c;
				b[y + 2][x] = b[y + 2][x + 1] = c;
				b[y + 3][x] = b[y + 3][x + 1] = c;
			}
		}
		color = b[ys][xs];
		if(color == -1) {//?????????????????????????????????
			printf("NG\n"); continue;
		}
		used[ys][xs] = true;
		dfs(ys, xs, -1, -1);
		if(flag) printf("OK\n");
		else printf("NG\n");
	}
}

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

class Solve{
private:
    int board[101][101] = {{0},{0}};
    int board_weight;
    int board_hight;
    int start_x;
    int start_y;
    int goal_x;
    int goal_y;
    int start_color;
    const int vector_x[4] = {0, 0, -1, 1};
    const int vector_y[4] = {1, -1, 0, 0};
    bool flag = false;
    void dfs(int x, int y);
public:
    Solve(int Board_Weight, int Board_Hight, int Start_X, int Start_Y, int Goal_X, int Goal_Y);
    void set_Block(int Color, int Direction, int X, int Y);
    bool check();
};

Solve::Solve(int Board_Weight, int Board_Hight, int Start_X, int Start_Y, int Goal_X, int Goal_Y){
    board_weight = Board_Weight;
    board_hight  = Board_Hight;
    start_x      = Start_X - 1;
    start_y      = Start_Y - 1;
    goal_x       = Goal_X - 1;
    goal_y       = Goal_Y - 1;
}
void Solve::set_Block(int Color, int Direction, int X, int Y){
    X -= 1; Y -= 1;
    if(X == start_x && Y == start_y){
        start_color = Color;
    }
    if(Direction == 0){
        for(int h = 0;h < 2;h++){
            for(int w = 0;w < 4;w++){
                board[Y+h][X+w] = Color;
            }
        }
    }else{
        for(int h = 0;h < 4;h++){
            for(int w = 0;w < 2;w++){
                board[Y+h][X+w] = Color;
            }
        }
    }
}
bool Solve::check(){
    Solve::dfs(start_x, start_y);
    return flag;
}

void Solve::dfs(int X, int Y){
    if(X == goal_x && Y == goal_y){
        flag = true;
        return;
    }
    
    for(int y = 0;y < 4;y++){
        for(int x = 0;x < 4;x++){
            int new_x = X + vector_x[x];
            int new_y = Y + vector_y[y];
            
            if(new_x >= 0 && new_x < board_weight){
                if(new_y >= 0 && new_y < board_hight){
                    if(start_color == board[new_y][new_x]){
                        board[Y][X] = 9;
                        dfs(new_x, new_y);
                    }
                }
            }
        }
    }
    return;
}

int main()
{
    int w, h, sx, sy, gx, gy, n, c, d, x, y;
    
    while(true){
        cin >> w >> h;
        if(w != 0 && h != 0){
            cin >> sx >> sy >> gx >> gy >> n;
            Solve s(w, h, sx, sy, gx, gy);
            
            for(int i = 0;i < n;i++){
                cin >> c >> d >> x >> y;
                s.set_Block(c, d, x, y);
            }
            
            if(s.check() == true){
                cout << "OK" << endl;
            }else{
                cout << "NG" << endl;
            }
        }else{
            break;
        }
    }
    
    return 0;
}

C++: #include <iostream>
#include <algorithm>
#include <queue>
#include <utility>
#include <string>

#define Pa pair<int,int>

using namespace std;

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

string bfs(int a[101][101], int sx, int sy, int gx, int gy, int w, int h)
{
	int s, t, m = a[sy][sx];
	bool vis[101][101];
	string str = "NG";
	queue<Pa> que;
	Pa pa;
	fill(&vis[0][0], &vis[h+1][w+1], true);
	
	que.push(Pa(sy, sx));
	vis[sy][sx] = false;
	
	while(!que.empty()){
		pa = que.front();
		que.pop();
		if(pa.first == gy && pa.second == gx){
			str = "OK";
			break;
		}
		
		for(int i = 0; i < 4; i++){
			s = pa.first + dy[i];
			t = pa.second + dx[i];
			if(1 <= s && s <= h && 1 <= t && t <= w){
				if(vis[s][t] && m == a[s][t]){
					que.push(Pa(s, t));
					vis[s][t] = false;
				}
			}
		}
	}
	
	return str;
}

int main()
{
	int a[101][101], w, h, sx, sy, gx, gy, s, t, u, v, n;
	
	while(1){
		cin >> w >> h;
		if(w == 0 && h == 0){
			break;
		}
		fill(&a[0][0], &a[h+1][w+1], -1);
		cin >> sx >> sy;
		cin >> gx >> gy;
		cin >> n;
		
		while(n--){
			cin >> s >> t >> u >> v;
			if(t == 0){
				for(int i = v; i <= v+1; i++){
					for(int j = u; j <= u+3; j++){
						a[i][j] = s;
					}
				}
			} else {
				for(int i = v; i <= v+3; i++){
					for(int j = u; j <= u+1; j++){
						a[i][j] = s;
					}
				}
			}
		}
		
		cout << bfs(a, sx, sy, gx, gy, w, h) << endl;
	}
	
	return 0;
}