「数据结构」: 间接寻址

　　间接寻址(indirect addressing)是公式化描述和链表描述的组合。采用这种方法，可以保留公式化描述方法的许多优点，在单位时间内访问每个元素，可采用二叉搜索方法在对数时间内对一个有序表进行搜索等等。与此同时，也可以获得链表描述方法的重要特色－－－在诸如插入和删除操作期间不必对元素进行实际的移动。因些，大多数间接寻址链表操作的时间复杂度都有元素的总数无关。

　　说到底，间接寻址只是一个每链只有一个节点的邻接矩阵。实现起来简单方便，兼具顺序表与链表的优点。

　　本次程序采用仍使用C++语言实现，为保证通用性使用模板机制。

　　程序结构：

　　　　　　1、IndirectAddr.h

　　　　　　2、excp.h

　　　　　　3、IndirectAddr.cpp

/*IndirectAddr.h*/
#ifndef __INDIRECTADDR__
#define __INDIRECTADDR__
#include "excp.h"
#include <iostream>
using namespace std;
template<class T>
class IndirectAddr {
public:
    IndirectAddr(int maxaSize = 10);
    ~IndirectAddr();
    bool isEmpty() const {return length == 0;}
    int getLength() const {return length;}
    bool findElement(int k, T& x) const;
    int searchElement(const T& x) const;
    IndirectAddr<T>& deleteElement(int k, T& x);
    IndirectAddr<T>& insertElement(int k, const T& x);
    void output(ostream& out) const;
private:
    T **table;
    int length;
    int maxSize;
};

template<class T>
IndirectAddr<T>::IndirectAddr(int maxaSize)
{
    maxSize = maxaSize;
    length = 0;
    table = new T *[maxSize];
}

template<class T>
IndirectAddr<T>::~IndirectAddr()
{
    for (int i = 0; i < length; i++)
        delete table[i];
    delete [] table;
}

template<class T>
bool IndirectAddr<T>::findElement(int k, T& x) const
{
    if (k<1 || k>length)
        return false;
    x = *table[k-1];
    return true;
}

template<class T>
int IndirectAddr<T>::searchElement(const T& x) const
{
    for (int i=0; i<length; i++)
        if (*table[i] == x)
            return i+1;
    return 0;
}

template<class T>
IndirectAddr<T>& IndirectAddr<T>::deleteElement(int k, T& x)
{
    if (findElement(k, x))
    {
        for (int i=k; i<length; i++)
            table[i-1] = table[i];
        length--;
        return *this;
    }
    else
        throw OutOfBounds();
}

template<class T>
IndirectAddr<T>& IndirectAddr<T>::insertElement(int k, const T& x)
{
    if (k<1 || k>length+1)
        throw OutOfBounds();
    if (length == maxSize)
        throw FullMemory();
    for (int i=length-1; i>=k-1; i--)
        table[i+1] = table[i];
    table[k-1] = new T;
    *table[k-1] = x;
    length++;
    return *this;
}

template<class T>
void IndirectAddr<T>::output(ostream& out) const
{
    for(int i=0; i<length; i++)
        out<<*table[i]<<" ";
    out<<endl;
}

template<class T>
ostream& operator<<(ostream& out, IndirectAddr<T>& x)
{
    x.output(out);
    return out;
}
#endif

/*excp.h*/
#ifndef _EXCP_
#define _EXCP_
#include <new>
using namespace std;

class OutOfBounds {
public:
    OutOfBounds(){}
};

class FullMemory {
public:
    FullMemory(){}
};

void my_new_handler()
{
    throw FullMemory();
}

new_handler old_handler = set_new_handler(my_new_handler);
#endif

/*IndirectAddr.cpp*/
#include <iostream>
#include "IndirectAddr.h"
#include "excp.h"
using namespace std;
int main()
{
    try{
        IndirectAddr<int> L;
        cout<<"Length = "<<L.getLength()<<endl;
        cout<<"IsEmpty = "<<L.isEmpty()<<endl;
        L.insertElement(1 ,2).insertElement(2, 6).insertElement(2, 3).
        insertElement(3, 6);
        cout<<"List is "<<L<<endl;
        cout<<"IsEmpty ="<<L.isEmpty()<<endl;
        int c;
        L.findElement(1, c);
        cout<<"First element is "<<c<<endl;
        cout<<"Length = "<<L.getLength()<<endl;
        L.deleteElement(3, c);
        cout<<"Delete element is "<<c<<endl;
        cout<<"List is "<<L<<endl;
    }
    catch(...)
    {
        cerr<<"This is a error"<<endl;
    }
    return 0;
}

总结：

        注意在使用table表内指针之前要先初始化，即分配一个T*类型空间。容易遗忘。