hashset.h

一个拼写检查程序

// template hash set class

#ifndef  _HASHSET_H_
#define  _HASHSET_H_

#include <iostream>
#include <vector>
#include <algorithm>
#include <stdexcept>

using namespace std;

// we do not compute prime numbers but use a table instead
static const int num_primes = 25;
static const unsigned long prime_list[] = {
            53, 97, 193, 389, 769, 1543, 3079, 6151, 12289, 24593, 49157, 98317,
            196613, 393241, 786433, 1572869, 3145739, 6291469, 12582917, 25165843,
            50331653, 100663319, 201326611, 402653189, 805306457
        };

template <typename key_type, typename hash_func, typename key_equal>
class HashSet {

protected:
    // hashtable entries
    class Entry {
    public:
        key_type key;
        bool used;

        Entry() : used(false) {}}
    ;

    int entries;      // number of entries
    int prime;        // index to size table

    vector<Entry> *ht;
    hash_func hf;        // hash function on key_type
    key_equal eq;        // equality predicate on key_type

    int table_size() const { return prime_list[prime];}
    float load_factor() const { return float(size()) / table_size();}
    int resize();

public:

    HashSet()
            : entries(0), prime(0),
    ht(new vector<Entry>(prime_list[0])) {}

    virtual ~HashSet() {
        delete ht;
    }

    virtual int size() const { return entries;}
    virtual bool search(const key_type& k);
    virtual void insert(const key_type& k);
    virtual void remove(const key_type& k);
};

#endif