void path_finding(int x,int y){

vector<vector<int> >used;
vector<vector<CellType> > cells = world.getCells();
vector<Trooper>troopers = world.getTroopers();

for(int i = 0; i<world.getWidth(); i++){
    vector<int> temp;
    for(int j=0; j<world.getHeight(); j++)
        temp.push_back(-1);
    used.push_back(temp);
}
    vector<pair<int,int> > oldwave,wave;
    const int dy[]={0,1,0,-1},dx[]={1,0,-1,0};
    int step=0,nx=0,ny=0;
    used.at(self.getX()).at(self.getY())=step;
    oldwave.push_back(make_pair(self.getX(),self.getY()));

    while(!oldwave.empty()){
        wave.clear();
        ++step;
        for(vector<pair<int,int> >::iterator i = oldwave.begin();i!=oldwave.end();i++){
            for(int d=0;d<4;++d){
                int nx=i->first+dx[d];
                int ny=i->second+dy[d];
                if(nx==-1 || ny==-1
                    || nx==30
                    || ny==20
                    || used.at(nx).at(ny)!=-1)continue;
                if(cells[nx][ny]==FREE && used[nx][ny]!=WALL ||(nx==x&&ny==y)){
                    wave.push_back(make_pair(nx,ny));
                    used.at(nx).at(ny)=step;
                }
                if(nx==x&&ny==y)
                    goto done;
            }
        }
        oldwave=wave;
    }
done:
    wave.clear();

    while(used[x][y]!=1 && used[x][y]!=-1){
        for(int d=0;d<4;++d){
            int nx=x+dx[d],ny=y+dy[d];
            if(nx==-1 || ny==-1
                || nx==30
                || ny==20
                || cells[nx][ny]!=FREE
                || used.at(nx).at(ny) == WALL)continue;
            if(used.at(nx).at(ny) < used[x][y]){
                wave.push_back(make_pair(nx,ny));
                x=nx;y=ny;
                break;
            }
        }
    }
}