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<string>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<complex>
#include<cmath>
#include<algorithm>
#include<map>
#include<vector>
#include<sstream>
#include<iostream>
#include<queue>
using namespace std;
const int dx[] = {1,0,-1,0},dy[] = {0,1,0,-1};
struct point{
    int x,y;
    point(){}
    point(int a, int b){x = a;y = b;}
};
int main(void){

    int w,h;
    while(cin>>w>>h,w){
        int xs,ys,xg,yg,n;
        cin>>xs>>ys>>xg>>yg>>n;
        int field[120][120] = {{0}};
        for(int i = 0;i < n;i++){
            int c,d,x,y;
            int dw = 4,dh = 2;
            cin>>c>>d>>x>>y;
            if(d)swap(dw,dh);
            for(int di = y;di < dh + y; di++){
                for(int dj = x;dj < dw + x;dj++){
                    field[di][dj] = c;
                }
            }
        }
        int C = field[xs][ys];
        bool vis[120][120] = {{false}};
        queue<point> Q;
        Q.push(point(xs,ys));
        if(field[xg][yg] != C || C == 0)cout<<"NG"<<endl;
        else {
            while(!Q.empty()){
                point P = Q.front();
                Q.pop();
                for(int i = 0;i < 4;i++){
                    point p = point(P.x + dx[i],P.y + dy[i]);
                    if(0 <= p.x && p.x <= w && 0 <= p.y && p.y <= h){
                        if(!vis[p.x][p.y]&&field[p.x][p.y] == C){

                            vis[p.x][p.y] = true;
                            Q.push(p);
                        }
                    }
                }
            }

        if(vis[xg][yg])cout<<"OK"<<endl;
        else cout<<"NG"<<endl;
        }
/*
        for(int i = 0;i < h;i++){
            for(int j = 0;j < w;j++){
                cout<<field[i][j]<<" ";
            }
            cout<<endl;
        }
        cout<<endl<<endl;
        for(int i = 0;i < h;i++){
            for(int j = 0;j < w;j++){
                cout<<vis[i][j]<<" ";
            }
            cout<<endl;
        }*/
        //cout<<C<<"---"<<field[xg][yg]<<endl;
    }


    return 0;
}

C++: #include<iostream>
using namespace std;
int data[102][102];
void DFS(int x,int y,int gx,int gy,bool &Flag,int color){
  if((data[y][x]!=color)||(Flag==true))
    return;
  if((x==gx)&&(y==gy)){
    Flag=true;
    return;
  }
  data[y][x]=0;
  DFS(x,y+1,gx,gy,Flag,color);
  DFS(x,y-1,gx,gy,Flag,color);
  DFS(x+1,y,gx,gy,Flag,color);
  DFS(x-1,y,gx,gy,Flag,color);
}
int main(){
  int w,h;
  int sx,sy;
  int gx,gy;
  while(1){
    cin>>w>>h;
    if(!w&&!h)
      break;
    for(int i=0;i<102;i++){
      for(int j=0;j<102;j++){
        data[i][j]=0;
      }
    }
    cin>>sx>>sy;
    cin>>gx>>gy;
    int n;
    cin>>n;
    int c,d,x,y;
    for(int i=0;i<n;i++){
      cin>>c>>d>>x>>y;
      if(d){
        for(int j=0;j<4;j++){
          for(int z=0;z<2;z++){
            data[j+y][z+x]=c;
          }
        }
      }else if(!d){
        for(int j=0;j<2;j++){
          for(int z=0;z<4;z++){
            data[j+y][z+x]=c;
          }
        }
      }
    }
    bool Flag=false;
    int color=data[sy][sx];
    if(color!=0)
      DFS(sx,sy,gx,gy,Flag,color);
    if (Flag){
      cout<<"OK"<<endl;
    }else if(!Flag){
      cout<<"NG"<<endl;
    }
  }
  return 0;
}

C++: #include <iostream>
#include <vector>
#include <cstring>

using namespace std;

#define repeat(n, i) for(int i=0; i<(n); i++)
int w, h;
int xs, ys;
int xg, yg;
int n;

int st_color;

int board[300][300];

#define VISITED 6

bool get_input() {
    memset(board, 0, sizeof(board));
    cin >> w >> h;
    if (w == 0 && h == 0) return false;
//    board.resize(h);
//    repeat(h, i) board[i].resize(w);
    cin >> xs >> ys;
    cin >> xg >> yg;
    cin >> n;
    repeat(n, i) {
        int c, d, x, y;
        cin >> c >> d >> x >> y;
        if (d == 1) {
            for (int j = y-1; j < y-1+4; j++) {
                for (int k = x-1; k < x-1+2; k++) {
                    board[j][k] = c;
                }
            }
        } else {
            for (int j = y-1; j < y-1+2; j++) {
                for (int k = x-1; k < x-1+4; k++) {
                    board[j][k] = c;
                }
            }
        }
    }
    st_color = board[ys-1][xs-1];
    return true;
}

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

bool possible;
void dfs(int x, int y) {
    board[y-1][x-1] = VISITED;
    if (x == xg && y == yg) {
        possible = true;
        return;
    }
    repeat(4, i) {
        int nx = x+dx[i], ny = y+dy[i];
        if (1 <= nx && nx <= w && 1 <= ny && ny <= h) {
            if (board[ny-1][nx-1] == st_color) {
                dfs(nx, ny);
            }
        }
    }
}

// debug 
//void solve() {
//    repeat(h, i) {
//        repeat(w, j) {
//            cout << board[i][j] << ' ';
//        }
//        cout << endl;
//    }
//}

void solve() {
    possible = false; dfs(xs, ys);
    if (possible) cout << "OK" << endl;
    else cout << "NG" << endl;
}

int main() {
    while (get_input()) {
        solve();
    }
    return 0;
}