hashtable的C++实现

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#include <vector>#include <list>using namespace std;template <typename HashedObj>class HashTable{  public:    explicit HashTable(int size = 101);    void makeEmpty()    {        for(int i = 0; i < theLists.size(); i++)            theLists[i].clear();    }    bool contains(const HashedObj & x) const    {        const list<HashedObj> & whichList = theLists[myhash(x)];        return find(whichList.begin(), whichList.end(), x) != whichList.end();    }    bool remove(const HashedObj & x)    {        list<HashedObj> & whichList = theLists[myhash(x)];        typename list<HashedObj>::iterator itr = find(whichList.begin(), whichList.end(), x);        if(itr == whichList.end())            return false;        whichList.erase(itr);        --currentSize;        return true;    }    bool insert(const HashedObj & x)    {        list<HashedObj> & whichList = theLists[myhash(x)];        if(find(whichList.begin(), whichList.end(), x) != whichList.end())            return false;        whichList.push_back(x);        if(++currentSize > theLists.size())            rehash();        return true;    }  private:    vector<list<HashedObj> > theLists;   // The array of Lists    int  currentSize;    void rehash()    {        vector<list<HashedObj> > oldLists = theLists;        // Create new double-sized, empty table        theLists.resize(2 * theLists.size());        for(int j = 0; j < theLists.size(); j++)            theLists[j].clear();        // Copy table over        currentSize = 0;        for(int i = 0; i < oldLists.size(); i++)        {            typename list<HashedObj>::iterator itr = oldLists[i].begin();            while(itr != oldLists[i].end())                insert(*itr++);        }    }    int myhash(const HashedObj & x) const    {        int hashVal = hash(x);        hashVal %= theLists.size();        if(hashVal < 0)            hashVal += theLists.size();        return hashVal;    }};
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