[算法学习]A*求第k短路

int cnt;
int Astar(){
    if(st == en) k++;
    if(dis[st] == inf) return -1;

    priority_queue<ptr> q;
    ptr cur{st, dis[st], 0};

    q.push(cur);
    while(!q.empty()){
        ptr t = q.top();
        q.pop();
        int nt = t.now;

        if(nt == en) cnt++;
        if(cnt == k) return t.g;
        for(int i = 0; i < edges[nt].size(); i++){
            int path = t.g + edges[nt][i].w;
            int now = edges[nt][i].to;
            q.push(ptr{now, path + dis[now], path});
        }
    }
    return -1;
}

struct ptr{
    int now, F, g; // 当前点编号， 估价函数F， 当前路径g
    bool operator <(const ptr& a) const {
        if(this->F == a.F) return this->g > a.g;
        return this->F > a.F;
    }
};