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;
int w,h,xs,ys,n,xg,yg,c,d,x,y,area[105][105],c_area[105][105];
int x_p[4]={-1,0,1,0},y_p[4]={0,-1,0,1};

bool flag=false;
void solve(int x,int y,int c);

int main(){
    while(1){
        cin >> w >> h;
        if(w==0&&h==0)break;
        cin >> xs >> ys >> xg >> yg >> n;
        for(int i=0;i<n;i++){
            cin >> c >> d >> x >> y;
            if(d==0){
            for(int j=y;j<y+2;j++){
                for(int k=x;k<x+4;k++){
                    area[k][j]=c;
                }
            }
            }else{
            for(int j=y;j<y+4;j++){
                for(int k=x;k<x+2;k++){
                    area[k][j]=c;
                    }
                }
            }
        }
        if(area[xs][ys]!=area[xg][yg]);
        else {
        solve(xs,ys,area[xs][ys]);
        }
        if(flag==true)cout << "OK" << endl;
        else cout << "NG" << endl;
        flag=false;
        fill(area[0],area[104],0);
    }

return 0;
}

void solve(int x,int y,int c){

    if(x==xg&&y==yg){
        flag=true;
    return;
    }else{
        for(int i=0;i<4;i++){
        if(area[x+x_p[i]][y+y_p[i]]==c){
                c_area[x][y]=area[x][y];
                area[x][y]=0;
                solve(x+x_p[i],y+y_p[i],c);
                area[x][y]=c_area[x][y];
            }
        }
    }
}

C++: #include <bits/stdc++.h>

#define FOR(i, j, k) for(int i = j; i < k; ++i)
#define rep(i, j) FOR(i, 0, j)
#define MAX 101

using namespace std;

int field[MAX][MAX];
int w, h;
int sx, sy, gx, gy;
int scol;
const int dx[] = {0, 1, 0, -1}, dy[] = {1, 0, -1, 0};

bool dfs(int x, int y) {
	field[y][x] = 0;
	if(x == gx && y == gy) return true;
	rep(i, 4) {
		int nx = x + dx[i];
		int ny = y + dy[i];
		if(nx <= w && nx > 0 && ny <= h && ny > 0) {
			if(field[ny][nx] == scol) dfs(nx, ny);
		}
	}
}

int main() {
	while(cin >> w >> h, w || h) {
		memset(field, 0, sizeof(field));
		int n;
		cin >> sx >> sy >> gx >> gy;
		cin >> n;
		rep(i, n) {
			int c, d, x, y;
			cin >> c >> d >> x >> y;
			rep(i, (d ? 4 : 2)) rep(j, (d ? 2 : 4)) field[y + i][x + j] = c;
		}
		rep(i, h) {
			rep(j, w) cout << field[i][j] << " ";
			cout << endl;
		}
		scol = field[sy][sx]; 
		if(dfs(sx, sy)) cout << "OK" << endl;
		else cout << "NO" << endl;
	}
	return 0;
}

C++: #include<iostream>
#include<queue>
#define MAX 100
using namespace std;

int map[MAX+2][MAX+2];
bool check[MAX+2][MAX+2];
int dx[4] = { -1,1,0,0};
int dy[4] = { 0,0,-1,1};

int main () {

  while ( true ) {

    queue<int> next;

    while( !next.empty() ) {
      next.pop();
    }
    
    int w,h;
    cin >> w >> h ;

    if ( w == 0 )
      break;

    int xs,ys;
    cin >> xs >> ys;
    
    int xg, yg;
    cin >> xg >> yg;

    int n;
    cin >> n;

    int c,d,x,y;

    for ( int i=0; i<MAX+2; i++ ) {
      for ( int j=0; j<MAX+2; j++ ) {
	map[i][j] = 0;
	check[i][j] = true;
      }
    }

    for ( int i=0; i<n; i++ ) {
      cin >> c >> d >> x >> y;
      
      //int count = 0;
      for ( int j=0; j<2; j++ ) {
	for ( int k=0; k<4; k++ ) {
	  //cout << count;
	  if ( d == 0 ) {
	    map[y+j][x+k] = c;
	  } else {
	    map[y+k][x+j] = c;
	  }
	}
      }
      //cout << endl;
    }

    next.push(ys*1000 + xs );

    int point;
    bool goal = false;

    int sc = map[ys][xs];

    /*
      for ( int i=0; i<=h; i++ ) {
      for ( int j=0; j<=w; j++ ) {
      cout << map[i+1][j+1];
      }
      cout << endl;
      }
      cout << endl;
    */
    int xn,yn;
    if ( map[yg][xg] == sc ) {
	while ( !next.empty() ) {
	  point = next.front();
	  next.pop();
	  xn = point%1000;
	  yn = point/1000;

	  if (map[yn][xn] == 0 )
	    continue;

	  if (point == yg*1000+xg) {
	    goal = true;
	    break;
	  }

	  for ( int i=0; i<4; i++ ) {
	    if ( check[yn+dy[i]][xn+dx[i]] ) {
	      check[yn+dy[i]][xn+dx[i]] = false;
	      if ( map[yn+dy[i]][xn+dx[i]] == sc ) {
		next.push((yn+dy[i])*1000+ xn +dx[i]);
	      }
	    }
	  }
	}

    }

    if ( goal )
      cout << "OK\n";
    else
      cout << "NG\n";
  }
}

C++: #include<iostream>
using namespace std;

int F[102][102];

void DFS(int Y,int X,int C){
   if(F[Y][X]!=C)
      return;
   F[Y][X]=6;
   DFS(Y-1,X,C);
   DFS(Y,X+1,C);
   DFS(Y+1,X,C);
   DFS(Y,X-1,C);
} 

int main(){
   int w,h,xs,ys,xg,yg,n;
   int c,d,x,y;
   while(true){
      cin >> w >> h;
      if(w==0&&h==0)
         break;
      cin >> xs >> ys;
      cin >> xg >> yg;
      cin >> n;
      for(int i=1;i<=n;i++){
         cin >> c >> d >> x >> y;
         if(d==0){
             F[x+1][y+1]=c;
             F[x+2][y+1]=c;
             F[x+3][y+1]=c;
             F[x+4][y+1]=c;  
             F[x+1][y+2]=c;
             F[x+2][y+2]=c;
             F[x+3][y+2]=c;
             F[x+4][y+2]=c;   
         }
         if(d==1){
             F[x+1][y+1]=c;
             F[x+1][y+2]=c;
             F[x+1][y+3]=c;
             F[x+1][y+4]=c;  
             F[x+2][y+1]=c;
             F[x+2][y+2]=c;
             F[x+2][y+3]=c;
             F[x+2][y+4]=c;   
         }
      }
      DFS(xs+1,ys+1,c);
      if(F[xg+1][yg+1]==6)
         cout << "OK" << endl;
      else
         cout << "NG" << endl;
      for(int i=1;i<=w;i++)
         for(int j=1;j<=h;j++)
            F[i][j]=0;
   }
   return 0;
}