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++: #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(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<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(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;
        }
      }
    }
  if(F[xs][ys] == 10){
cout << "NG" << endl;
continue;
  DFS(xs,ys,F[xs][ys]);
  
  if(F[xg][yg] == -1){
    cout << "OK" << endl;
  } else {
    cout << "NG" <<endl;
  }
  }
}