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 <bits/stdc++.h>
using namespace std;
const int limit = 100;
int w, h, n;
int xs, ys, xg, yg;
int maze[limit][limit];
int dx[4] = {1, -1, 0, 0};
int dy[4] = {0, 0, 1, -1};
int flag = 0;

void dfs(int x, int y){
    maze[x][y] = 0;
    //4近傍を探索
    for(int i=0; i < 4; i++){
            int nx = x + dx[i], ny = y + dy[i];
            if(0 <= nx and nx < h and 0 <= ny and ny < w and maze[nx][ny] != 0){
                if(nx == (xg-1) and ny == (yg-1)) flag = 1;
                dfs(nx, ny);
            }
        }
    return;
}


int main(){
    while(1){
    flag = 0;
    cin >> w >> h;
    if(w == 0 and h == 0) break;
    cin >> xs >> ys >> xg >> yg >> n;
    //ボードを初期化
    for(int i=0; i < w; i++)for(int j=0; j < h; j++) maze[i][j] = 0;
    //ボードにブロックを敷き詰める
    for(int i=0; i < n; i++){
        int c = 0, d = 0, x = 0, y = 0;
        cin >> c >> d >> x >> y;
        if(d)for(int dx=0; dx < 2; dx++)for(int dy=0; dy < 4; dy++) maze[x-1+dx][y-1+dy] = c;
        else for(int dy=0; dy < 2; dy++)for(int dx=0; dx < 4; dx++) maze[x-1+dx][y-1+dy] = c;
    }
    //迷路を単純化する
    for(int i=0; i < w; i++)for(int j=0; j < h; j++) if(maze[i][j] != maze[xs][ys]) maze[i][j] = 0;

    //search
    dfs(xs-1, ys-1);
    if(flag) cout << "OK" << endl;
    else cout << "NG" << endl;
    }
    return 0;
}

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

int w, h, n;
int sx, sy, gx, gy;
int t[102][102];

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

bool check(int x, int y, int c){
  if(x == gx && y == gy) return true;

  t[y][x] = -1;

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

    if(nx < 0 || w <= nx || ny < 0 || h <= ny || t[ny][nx] != c) continue;
    if(check(nx, ny, c)) return true;
  }
}

void putBlock(int c, int d, int x, int y){
  int addX = (d == 0 ? 4 : 2);
  int addY = (d == 0 ? 2 : 4);

  for(int i = y; i < y + addY; i++){
    for(int j = x; j < x + addX; j++){
      t[i][j] = c;
    }
  }
}

int main(){
  while(cin >> w >> h, w || h){
    cin >> sx >> sy; sx--; sy--;
    cin >> gx >> gy; gx--; gy--;
    cin >> n;

    memset(t, -1, sizeof(t));

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

      x--;
      y--;
      putBlock(c, d, x, y);
    }

    if(t[sy][sx] != -1 && check(sx, sy, t[sy][sx])){
      cout << "OK\n";
    }
    else{
      cout << "NG\n";
    }
  }
}

C++: #include <iostream>
using namespace std;
  
int F[105][105];
int xg,yg,w,h;
  
  
void DFS(int Y,int X,int c){
  if(F[Y][X] != c){
    return;
  }
  
  F[Y][X] = -1;
  DFS(Y+1,X  ,c);
  DFS(Y-1  ,X,c);
  DFS(Y,X+1  ,c);
  DFS(Y  ,X-1,c);
}
  
  
int main(){
  int xs,ys,n;
  while(1){
    cin >> w >> h;
    if(w == 0 && h == 0)
      break;
for(int i=0; i<105; i++){
      for(int j=0; j<105; j++){
        F[i][j]=10;
      }
    }
      
    cin >> xs >> ys >> xg >> yg >> n;
  
  
    for(int i=0;i<n;i++){
      int c,d,x,y;
      cin >> c >> d >> x >> y;
      if(c == 0)
        c = 2345;
      if(d == 0){
        for(int j=0;j<4;j++){
          F[x+j][y] = c;
          F[x+j][y+1] = c;
        }
      } else {
        for(int j=0;j<4;j++){
          F[x][y+j] = c;
          F[x+1][y+j] = c;
        }
      }
    }
 
  DFS(xs,ys,F[xs][ys]);
  
  if(F[xg][yg] == -1){
    cout << "OK" << endl;
  } else {
    cout << "NG" <<endl;
  }
  }
}

C++: #include <iostream>
using namespace std;
  
int F[105][105];
int xg,yg,w,h;
  
  
void DFS(int Y,int X,int c){
  if(F[Y][X] != c){
    return;
  }
  
  F[Y][X] = -1;
  DFS(Y+1,X  ,c);
  DFS(Y-1  ,X,c);
  DFS(Y,X+1  ,c);
  DFS(Y  ,X-1,c);
}
  
  
int main(){
  int xs,ys,n;
  while(1){
    cin >> w >> h;
    if(w == 0 && h == 0)
      break;
for(int i=0; i<102; i++){
      for(int j=0; j<102; j++){
        F[i][j] = 10;
      }
    }
      
    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 == 0){
        for(int j=0;j<4;j++){
          F[x+j][y] = c;
          F[x+j][y+1] = c;
        }
      } else {
        for(int j=0;j<4;j++){
          F[x][y+j] = c;
          F[x+1][y+j] = c;
        }
      }
    }
  DFS(xs,ys,F[xs][ys]);
  
  if(F[xg][yg] == -1){
    cout << "OK" << endl;
  } else {
    cout << "NG" <<endl;
  }
  }
}

C++: #include<iostream>

int field[102][102];//y,x
bool flag;
int n,sx,sy,gx,gy,col;

void erase(){
	for(int i=0; i<102; i++)
		for(int j=0; j<102; j++)
			field[i][j] = 0;
}

void DFS(int x, int y){
	int xx = x+1;
	int yy = y;

	if(xx == gx && yy == gy){
		flag = true;
		return;
	}

	if(field[yy][xx] == col)
		DFS(xx, yy);
	if(flag)
		return;

	xx = x;
	yy = y+1;
	if(field[yy][xx] == col)
		DFS(xx, yy);
	if(flag)
		return;

	xx = x-1;
	yy = y;
	if(field[yy][xx] == col)
		DFS(xx, yy);
	if(flag)
		return;
			
	xx = x;
	yy = y-1;
	if(field[yy][xx] == col)
		DFS(xx, yy);
}

int main(){
	int c,d,bx,by;
	using std::cin;
	while(true){
		flag = false;
		erase();
		cin >> c >> d;
		if(!c && !d)
			return 0;
		cin >> sx >> sy;
		cin >> gx >> gy;
		cin >> n;
		for(int i=0; i<n; i++){
			cin >> c >> d >> bx >> by;
			if(d==0){
				for(int h=by; h<by+2; h++)
					for(int k=bx; k<bx+4; k++)
						field[h][k] = c;
			}
			else{
				for(int h=by; h<by+4; h++)
					for(int k=bx; k<bx+2; k++)
						field[h][k] = c;
			}
		}
		col = field[gy][gx];
		DFS(sx, sy);
		if(flag)
			std::cout << "OK\n";
		else
			std::cout << "NG\n";
	}
}