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; flag = false;
		dfs(ys, xs, -1, -1);
		if(flag) printf("OK\n");
		else printf("NG\n");
	}
}

C++: #include<iostream>
#include<cstdio>
#include<queue>
using namespace std;
#define MAX 101
#define Nll -1
int w,h;
int xs,ys,xg,yg;
int blockNm;
int map[MAX][MAX];
typedef queue < pair<int,int> > Queue;
void setBlock(int color,int dir,int x,int y){
	int dx[]={2,0};
	int dy[]={0,2};
	int xb=x,yb=y;//x_base,y_base
	for(int i=0;i<2;i++,xb+=dx[dir],yb+=dy[dir]){
		map[yb][xb]
		        =map[yb][xb+1]
		        =map[yb+1][xb]
		        =map[yb+1][xb+1]=color;
	}
}
void init(){
	for(int i=0;i<MAX;i++)for(int j=0;j<MAX;j++)map[i][j]=-1;
}
void print(){
	for(int i=0;i<h;i++){for(int j=0;j<w;j++)printf("%2d",map[i][j]);cout<<endl;}
}
bool isGoal(int xs,int ys,int xg,int yg){
	int color=map[xs][ys];
	if(color==Nll)return false;
	int dx[]={ 0, 1, 0,-1};
	int dy[]={-1, 0, 1, 0};
	Queue q;
	q.push(pair<int,int>(xs,ys));
	while(!q.empty()){
		pair<int,int> cur=q.front();q.pop();
		if(cur.first==xg&&cur.second==yg)return true;
		map[cur.first][cur.second]=Nll;
		for(int i=0;i<4;i++){
			if(cur.first+dx[i]<1||cur.first+dx[i]>w
					||cur.second+dy[i]<1||cur.second+dy[i]>h
					||map[cur.first+dx[i]][cur.second+dy[i]]!=color)continue;
			q.push(pair<int,int>(cur.first+dx[i],cur.second+dy[i]));
		}
	}
	return false;
}
int main(){
	while(cin>>w>>h&&(w||h)){
		init();
		cin>>xs>>ys>>xg>>yg>>blockNm;
		for(int i=0;i<blockNm;i++){
			int color,dir,x,y;
			cin>>color>>dir>>x>>y;
			setBlock(color,dir,x,y);
		}
//		print();
		string ans=isGoal(xs,ys,xg,yg)?"OK":"NG";
		cout<<ans<<endl;
	}

	return 0;
}

C++: #include <iostream>
using namespace std;
struct cordinate{
        int y;
        int x;
};
cordinate SIZE,Start,Goal;
struct Blocks{
        int color;
        int direction;
        int y;
        int x;
};
Blocks block[200];
int N,board[200][200];
int Color,dp[200][200];
int recursion(int y,int x){
        int res=0;
        if(y==Goal.y && x==Goal.x){
                res=1;
        }
        else if(dp[y][x]!=-1)
                return dp[y][x];
        else{
                dp[y][x]=0;
                if(board[y+1][x]==Color && dp[y+1][x]==-1)
                        res+=recursion(y+1,x);
                if(board[y-1][x]==Color && dp[y-1][x]==-1)
                        res+=recursion(y-1,x);
                if(board[y][x+1]==Color && dp[y][x+1]==-1)
                        res+=recursion(y,x+1);
                if(board[y][x-1]==Color && dp[y][x-1]==-1)
                        res+=recursion(y,x-1);
        }
        return dp[y][x]=res;
}
int main(){
        while(true){
                for(int i=0 ; i<100 ; i++ )
                        for(int j=0 ; j<100 ; j++ )
                                dp[i][j]=-1;
                cin >> SIZE.x >> SIZE.y;
                if(SIZE.x+SIZE.y==0)
                        break;
                cin >> Start.x >> Start.y;
                cin >> Goal.x >> Goal.y;
                cin >> N;
                for(int i=0 ; i<N ; i++ ){
                        cin >> block[i].color >> block[i].direction;
                        cin >> block[i].x >> block[i].y;
                        if(block[i].direction){
                                for(int l=block[i].y ; l<block[i].y+4 ; l++ ){
                                        for(int j=block[i].x ; j<block[i].x+2 ; j++ ){
                                                board[l][j]=block[i].color;
                                        }
                                }
                        }
                        else{
                                for(int l=block[i].y ; l<block[i].y+2 ; l++ ){
                                        for(int j=block[i].x ; j<block[i].x+4 ; j++ ){
                                                board[l][j]=block[i].color;
                                        }
                                }
                        }
                }
                Color=board[Start.y][Start.x];
                if(recursion(Start.y,Start.x)>0)
                        cout <<"OK"<<endl;
                else
                        cout <<"NG"<<endl;
        }
        return 0;
}