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;
#define rep(i, n) for (int i = 0; i < (n); i++)
typedef long long ll;
typedef pair<int, int> P;

int dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};

int main() {
    while (true)
    {
        int w, h;
        cin >> w >> h;
        if (w == 0 && h == 0) break;

        int grid[100][100];
        rep(i, w) rep(j, h) grid[i][j] = 0;

        int sx, sy, gx, gy;
        cin >> sx >> sy >> gx >> gy;
        sx--; sy--; gx--; gy--;

        int n;
        cin >> n;

        rep(i, n) {
            int c, d, x, y;
            cin >> c >> d >> x >> y;
            if (d == 0) {
                rep(j, 4) rep(k, 2) grid[j+x-1][k+y-1] = c;
            } else {
                rep(j, 2) rep(k, 4) grid[j+x-1][k+y-1] = c;
            }
        }

        bool ok[100][100];
        rep(i, w) rep(j, h) ok[i][j] = true;

        bool flag = false;
        int sc = grid[sx][sy];
        queue<P> que;
        que.push(P(sx, sy));
        while (que.size()) {
            P p = que.front();
            que.pop();
            if (p.first == gx && p.second == gy) {
                flag = true;
                break;
            }

            rep(i, 4) {
                int nx = p.first+dx[i], ny = p.second+dy[i];
                if (0 <= nx && nx < w && 0 <= ny && ny < h && grid[nx][ny] == sc && ok[nx][ny] == true) {
                    que.push(P(nx, ny));
                    ok[nx][ny] = false;
                }
            }
        }

        if (flag && sc > 0) cout << "OK" << endl;
        else cout << "NG" << endl;
    }


    return 0;
}

C++: #include<bits/stdc++.h>
#define rep(i,n)for(int i=0;i<n;i++)
using namespace std;

int a[100][100];
int dx[]{ 1,-1,0,0 }, dy[]{ 0,0,1,-1 };
int w, h;

void dfs(int x, int y) {
	int c = a[x][y];
	a[x][y] = -1;
	rep(i, 4) {
		int nx = x + dx[i], ny = y + dy[i];
		if (0 <= nx&&nx < w && 0 <= ny&&ny < h&&a[nx][ny] == c)dfs(nx, ny);
	}
}
int main() {
	while (cin >> w >> h, w) {
		memset(a, 0, sizeof(a));
		int xs, ys, xg, yg, n;
		cin >> xs >> ys >> xg >> yg >> n;
		xs--; ys--; xg--; yg--;
		rep(i, n) {
			int c, d, x, y; scanf("%d%d%d%d", &c, &d, &x, &y);
			x--; y--;
			rep(j, 2)rep(k, 4) {
				if (d)a[x + j][y + k] = c;
				else a[x + k][y + j] = c;
			}
		}
		dfs(xs, ys);
		puts(a[xg][yg] == -1 ? "OK" : "NG");
	}
}

C++: #include<bits/stdc++.h>
using namespace std;

int xx[4] = {0, 1, 0, -1};
int yy[4] = {1, 0, -1, 0};
int block[100][100];
bool put[100][100];
int already[100][100];
int w, h;
int xs, ys;
int xg, yg;
bool dfs(int nex, int ney);

int main(){
  int n;
  
  while(1){
    memset(block, 0, sizeof(block));
    memset(already, 0, sizeof(already));
    memset(put, 0, sizeof(put));
    cin >> w >> h;
    if(w == 0 && h == 0) break;
    cin >> xs >> ys;
    cin >> xg >> yg;
    cin >> n;
    for(int i = 0; i < n; i++){
      int c, d, x, y;
      int wide, high;
      cin >> c >> d >> x >> y;
      if(d){
	wide = 2; high = 4;
      }
      else{
	wide = 4; high = 2;
      }
      for(int j = 0; j < high; j++){
	for(int k = 0; k < wide; k++){
	  block[y+j][x+k] = c;
	  put[y+j][x+k] = true;
	}
      }
    }
    bool ans = false;
    if(block[ys][xs] == block[yg][xg]){
      ans = dfs(xs, ys);
      if(ans) cout << "OK" << endl;
      else cout << "NG" << endl;
    }
    else cout << "NG" << endl;
  }
}

bool dfs(int nex, int ney){
  already[nex][ney] = 1;
  if(nex == xg && ney == yg) return true;
  for(int i = 0; i < 4; i++){
    int nx = nex + xx[i];
    int ny = ney + yy[i];
    if(0 <= nx && 0 <= ny && ny < h && nx < w && put[ny][nx] && !already[ny][nx] && block[ys][xs] == block[ny][nx]) return dfs(nx, ny);
  }
  return false;
}