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>
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 || Y > w || X > h){
    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] = 0;
      }
    }
      
    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 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;
          }
        }
      }
      /*
      for(int j=0;j<h+1;j++){
        for(int z=0;z<w+1;z++){
          cout<<data[j][z];
        }
        cout<<endl;
      }*/
    }
    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<bits/stdc++.h>
using namespace std;
int h,w;
int maps[101][101];
int check[101][101];
int dy[]={-1,0,1,0};
int dx[]={0,-1,0,1};
int color;
int sy,sx,gy,gx;
int by0[]={0,0,1,1,0,0,1,1};
int bx0[]={0,1,1,0,2,3,2,3};
int by1[]={0,0,1,1,2,3,2,3};
int bx1[]={0,1,1,0,0,0,1,1};

bool solve(int y,int x);
  
int main(){
  int n,c,d,x,y;
  while(cin>>w>>h,w|h){
    cin>>sx>>sy;
    cin>>gx>>gy;
    cin>>n;
    memset(check,0,sizeof(check));
    for(int i=0;i<n;i++){
      cin>>c>>d>>x>>y;
      x--;y--;
      if(d==0){
	for(int i=0;i<8;i++){
	  maps[y+by0[i]][x+bx0[i]]=c;
	}
      }
      if(d==1){
	for(int i=0;i<8;i++){
	  maps[y+by1[i]][x+bx1[i]]=c;
	}
      }
    }
    sy--;sx--;gy--;gx--;
    color=maps[sy][sx];
    if(solve(sy,sx))cout<<"OK"<<endl;
    else cout<<"NG"<<endl;
  }
}

bool solve(int y,int x){
  check[y][x]=1;
  if(y==gy && x==gx)return true;
  bool b=false;
  for(int i=0;i<4;i++){
    int ny=y+dy[i];
    int nx=x+dx[i];
    if(ny>=0 && ny<h && nx>=0 && nx<w && maps[ny][nx]==color && check[ny][nx]==0){
      b=b | solve(ny,nx);
    }
  }
  return b;
}

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