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 <cstring>
using namespace std;

bool b;
int dx[]={1,0,-1,0};
int dy[]={0,1,0,-1};
int board[105][105];
int xg , yg , sc;

void dfs(int x , int y ,int w , int h){
	if(x==xg&&y==yg) {
		b=true;
		return;
	}
	for(int i=0;i<4;++i){
		int tx=x+dx[i];
		int ty=y+dy[i];
		if(tx<=0 || ty<=0 || tx>w || ty>h || board[tx][ty]!=sc || board[tx][ty]==0 || b ) continue;
		dfs( tx , ty , w , h );
	}
}

int main(){
	int w , h;
	while(cin >> w >> h , w|h){
		int xs , ys , n;
		b=false;
		memset(board,0,sizeof(board));
		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){
				for(int k=y;k<y+2;++k){
					for(int j=x;j<x+4;++j){
						board[j][k]=c;
					}
				}
			} else {
				for(int k=y;k<y+4;++k){
					for(int j=x;j<x+2;++j){
						board[j][k]=c;
					}
				}
			}
		}
		sc=board[xs][ys];
		int gc=board[xg][yg];
		if(sc!=gc) {}
		else  dfs( xs , ys , w , h );
		cout << ( b ? "OK" : "NG") << endl;
	}
	return 0;
}

C++: #include <cstdio>
#include <cstring>
int block[100][100];
int visited[100][100];
bool memo[100][100];
int w, h, xs, ys, xg, yg, n;
int d[2][4]={{0,0,-1,1},{-1,1,0,0}};
bool dfs(int x, int y) {
    if (visited[y][x]) return memo[y][x];
    if (x==xg-1&&y==yg-1) return true;
    visited[y][x]=1;
    for (int i=0; i<4; i++) {
        int nx=x+d[0][i], ny=y+d[1][i];
        if (nx>=0&&nx<w&&ny>=0&&ny<h&&block[y][x]==block[ny][nx]) {
            if (dfs(nx,ny)) {
                memo[y][x]=true;
                return true;
            }
        }
    }
    memo[y][x]=false;
    return false;
}
int main() {
    while (scanf("%d%d",&w,&h)) {
        if (!w&&!h) break;
        for (int i=0; i<100; i++) for (int j=0; j<100; j++) {
            visited[i][j]=0;
            block[i][j]=0;
            memo[i][j]=false;
        }
        scanf("%d%d%d%d%d",&xs,&ys,&xg,&yg,&n);
        for (int i=0; i<n; i++) {
            int c, d, x, y;
            scanf("%d%d%d%d",&c,&d,&x,&y);
            if (d) {
                for (int j=y-1; j<y+3; j++) {
                    for (int k=x-1; k<x+1; k++) {
                        block[j][k]=c;
                    }
                }
            } else {
                for (int j=x-1; j<x+3; j++) {
                    for (int k=y-1; k<y+1; k++) {
                        block[k][j]=c;
                    }
                }
            }
        }
        /*for (int i=0; i<h; i++) for (int j=0; j<w; j++) {
            printf("%d%c",block[i][j],j==w-1?'\n':' ');
        }*/
        if (dfs(xs,ys)) puts("OK");
        else puts("NG");
    }
}