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++: // 2011/08/09 Tazoe

#include<iostream>
using namespace std;

bool DFS(int brd[102][102], int x, int y, int xg, int yg, int c)
{
	if(brd[y][x]!=c)
		return false;

	if(x==xg&&y==yg)
		return true;

	brd[y][x] = 9;		// ツつキツづづ可訪ツづェツつス

	if(DFS(brd, x+1, y, xg, yg, c))
		return true;
	if(DFS(brd, x, y+1, xg, yg, c))
		return true;
	if(DFS(brd, x-1, y, xg, yg, c))
		return true;
	if(DFS(brd, x, y-1, xg, yg, c))
		return true;

	return false;
}

int main()
{
	while(true){
		int w, h;
		cin >> w >> h;
		if(w==0&&h==0)
			break;

		int brd[102][102];
		for(int y=0; y<=h+1; y++)
			for(int x=0; x<=w+1; x++)
				brd[y][x] = 0;

		int xs, ys, xg, yg;
		cin >> xs >> ys;
		cin >> xg >> yg;

		int n;
		cin >> n;

		for(int i=0; i<n; i++){
			int c, d, x, y;
			cin >> c >> d >> x >> y;
			brd[y  ][x  ] = c;
			brd[y  ][x+1] = c;
			brd[y+1][x  ] = c;
			brd[y+1][x+1] = c;
			if(d==0){
				brd[y  ][x+2] = c;
				brd[y  ][x+3] = c;
				brd[y+1][x+2] = c;
				brd[y+1][x+3] = c;
			}
			else{
				brd[y+2][x  ] = c;
				brd[y+2][x+1] = c;
				brd[y+3][x  ] = c;
				brd[y+3][x+1] = c;
			}
		}

		if(brd[ys][xs]==0||brd[yg][xg]==0||brd[ys][xs]!=brd[yg][xg]){
			cout << "NG" << endl;
			continue;
		}

		if(DFS(brd, xs, ys, xg, yg, brd[ys][xs]))
			cout << "OK" << endl;
		else
			cout << "NG" << endl;
	}

	return 0;
}

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>
using namespace std;

int C[102][102];
int ans;
int xg,yg;

void meiro(int W,int H,int c){
  if(W==xg && H==yg){
    ans = 1;
    return;
  }

  if(C[W][H]!=c){
    return;
  }

  C[W][H] = '.';

  meiro(W-1,H  ,c);
  meiro(W  ,H+1,c);
  meiro(W+1,H  ,c);
  meiro(W  ,H-1,c);
}

int main(){
  while(1){
    for(int i=0;i<102;i++){
      for(int j=0;j<102;j++){
        C[i][j] = 0;
      }
    }
    
    int w,h;
    cin >> w >> h;

    if(w==0 && h==0){
      break;
    }

    int xs,ys;
    cin >> xs >> ys;

    cin >> xg >> yg;

    int n;
    cin >> n;
    int c[n],d[n],x[n],y[n];

    int cbase;

    for(int i=0;i<n;i++){
      cin >> c[i] >> d[i] >> x[i] >> y[i];

      if(d[i]==0){
        for(int j=x[i];j<x[i]+4;j++){
          for(int k=y[i];k<y[i]+2;k++){
            C[j][k]=c[i];
          }
        }
      }
      if(d[i]==1){
        for(int j=x[i];j<x[i]+2;j++){
          for(int k=y[i];k<y[i]+4;k++){
            C[j][k]=c[i];
          }
        }
      }

      if(x[i]==xs &&y[i]==ys){
        cbase = c[i];
      }
    }
    ans = 0;
    meiro(xs,ys,cbase);

    if(ans==1){
      cout << "OK" << endl;
    }else{
      cout << "NG" << endl;
    }
  }

  return 0;
}