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我正在实现六度凯文培根问题并为演员节点编写一个类。我可以使用 set 而不是 hash_set 容器来保存用户定义的类。为什么?错误消息显示:错误 C2440: 'type cast' : cannot convert from 'const ActorGraphNode' to 'size_t' 1> 没有可以执行此转换的用户定义转换运算符,或者无法调用该运算符....

#include <hash_set>
#include <set>
class ActorGraphNode{
    public: 
    string ActorName;
    //hash_set<ActorGraphNode> linkedActors;
    set<ActorGraphNode> linkedActors;
    ActorGraphNode(string name):ActorName(name){}
    void linkCostar(ActorGraphNode actor){
       linkedActors.insert(actor);
       actor.linkedActors.insert(*this);
    }
    bool operator<( const ActorGraphNode& a ) const
    { return ActorName < a.ActorName ? true : false;}
};
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2 回答 2

1

不出所料,hash_set需要您为您的类型实现哈希函数。

class ActorGraphNode{
    public: 
    string ActorName;
    hash_set<ActorGraphNode> linkedActors;
    //set<ActorGraphNode> linkedActors;
    ActorGraphNode(string name):ActorName(name){}
    void linkCostar(ActorGraphNode actor){
       linkedActors.insert(actor);
       actor.linkedActors.insert(*this);
    }
    bool operator<( const ActorGraphNode& a ) const
    { return ActorName < a.ActorName;}
    bool operator ==( const ActorGraphNode& a ) const
    { return ActorName == a.ActorName;}
    operator size_t() const
    {
      return hash<string>()(ActorName);
    }
};
于 2013-05-29T21:26:55.620 回答
0

感谢大家的回答和评论。这是我在您的帮助下更新的代码。加上函数 linkCostar() 我现在使用通过引用传递:

class ActorGraphNode{
public: 
    string ActorName;
    hash_set<ActorGraphNode> linkedActors;
    ActorGraphNode(string name):ActorName(name){}
    void linkCostar(ActorGraphNode& actor){
        linkedActors.insert(actor);
        actor.linkedActors.insert(*this);
    }
    bool operator==( const ActorGraphNode& a ) const
    { return ActorName == a.ActorName ? true : false;}
    operator size_t() const
    {
        const int HASHSIZE = 501;
        int seed = 131;
        size_t sum = 0;
        for(size_t i = 0; i < ActorName.length(); ++i) 
            sum = (sum * seed) + ActorName[i];      
        return sum % HASHSIZE;
    }
};
于 2013-05-29T21:58:51.733 回答