【算法与数据结构】哈希表-链地址法

//链表结点
typedef struct _tagNode
{
    int data;              //元素值（关键字）
    struct _tagNode* next; //下一个结点
}Node, *PNode;

//哈希表结点
typedef struct _tagHashTable
{
    //这里用一个联合体来解释一下，其index也即哈希值
    union{
        int index;            //哈希表index（这里也是哈希值）
        int nHashValue;       //也即哈希值
    }INDEX;

    Node* firstChild;     //该哈希结点在第一个子节点，即哈希值为该结点INDEX字段的
    struct _tagHashTable* next; //指向下一个哈希结点
}HashTable, *PHashTable;

//pHashTable 哈希表头结点
//length 哈希表长度
//pArr 关键字元素数组
//nums 关键字元素数组长度
void CreateHashTable(PHashTable& pHashTable, int length, int* pArr, int nums)
{
    pHashTable = new HashTable();
    if(NULL == pHashTable) { cerr << "Create Hashtable error! \n"; return;}
    pHashTable->firstChild = NULL;
    pHashTable->INDEX = 0; 
    pHashTable->next = NULL;

    PHashTable pTemp = pHashTable;

    for (int i = 1; i < length; ++ i)
    { 
        PHashTable pt = new HashTable();
        if(NULL == pt) {cerr << "Create Hahstable error ! \n"; return;}

        pt->firstChild = NULL;
        pt->INDEX = i;
        pt->next = NULL;

        pTemp->next = pt;
        pTemp = pt;

    } //for 

    //Hash(key) = key MOD length;
    for(int i = 0; i < nums; ++ i)
    {
        //计算哈希值
        int nHashValue = pArr[i] % length;
        PHashTable pTemp2 = NULL;
        if(NULL != (pTemp2 = LocateHashNode(pHashTable, nHashValue)) )
        {
            Insert(pTemp2, pArr[i]);
        }
        else
        {
            cerr << "元素值为 "<< pArr[i]<< " 的元素，哈希值为 "<< nHashValue<< ", 查找其所在哈希结点失败"<<endl;
        }
    }
 
}

//将关键字插入所在的pHashtable结点的链表
//返回其在该链表上的位置（下标从1开始）
int Insert(PHashTable& pHashtable, int data)
{
    if(NULL == pHashtable){cerr << "当前哈希表结点为空 \r\n"; return -1;}

    int nIndex = 1;
    PNode pNewNode = new Node();
    if(NULL == pNewNode){cerr << "建立新链表结点失败"<<endl; return -1;}

    pNewNode->data = data;
    pNewNode->next = NULL; 

    PNode pNode = pHashtable->firstChild;
    if (NULL == pNode)
    {
        pHashtable->firstChild = pNewNode;
    }
    else
    {
        while(pNode->next != NULL)
        {
            ++ nIndex;
            pNode = pNode->next;
        }
        ++nIndex;

        pNode->next = pNewNode;

    }  


    cout << "元素 "<< data << " 插入在了哈希表结点 "<< pHashtable->INDEX<< " 的第 "<< nIndex<< " 个位置"<<endl;
    return nIndex;
}

//根据哈希值，返回该值应该所在的哈希表结点指针
//pHashtable 哈希表头结点
//nHashValue 元素的哈希值
PHashTable LocateHashNode(PHashTable& pHashtable, int nHashValue)
{
    if(NULL == pHashtable) {cerr << "哈希表头结点为空"<<endl; return NULL;}

    PHashTable pTemp = pHashtable;

    do 
    {
        if (pTemp->INDEX == nHashValue) return pTemp;
        pTemp = pTemp->next;

    } while (pTemp != NULL);

    return NULL;
}

    
//查找头结点为pHashtable的哈希表
//其数据为data，哈希值为nHashValue的元素
//在哈希表某个结点的链表中的位置（下标从1开始）
int Find(PHashTable& pHashtable, int data, int nHashValue)
{
    if(NULL == pHashtable){cerr << "哈希表头结点为空"<<endl; return -1;}

    PHashTable pHashNode = LocateHashNode(pHashtable, nHashValue);
    if(NULL == pHashNode) {cerr << "找不到元素 " << data << " ，其哈希值为 "<<nHashValue<< " 在哈希表中的位置"; return -1;}

    int nINDEX = 1;
    PNode pNode = pHashNode->firstChild;
    if (NULL == pNode)
    {
        {cerr << "找不到元素 " << data << " ，其哈希值为 "<<nHashValue<< " 在哈希表中的位置"; return -1;}
    }
    else
    { 
        bool b = false;

        while(pNode != NULL)
        {
            if(pNode->data == data)
            {
                b = true;
                break;
            }
            ++ nINDEX;
            pNode = pNode->next;
        } 

        if (false == b)
        {
            cerr << "找不到元素 " << data << " ，其哈希值为 "<<nHashValue<< " 在哈希表中的位置"; 
            return -1;
        }
        else
        {
            cout << "元素 "<< data << " 插入在了哈希表结点 "<< pHashNode->INDEX<< " 的第 "<< nINDEX<< " 个位置"<<endl; 
        }
    }  


    return nINDEX;
}

int _tmain(int argc, _TCHAR* argv[])
{
    PHashTable pHashtable = NULL;
    int length = 0;
    int nums = 0;

    cout <<endl<< "请输入元素个数:";
    cin >> nums;
    int* pArr = new int[nums]();
    if(NULL == pArr) {cerr<<"申请元素空间错误"; return -1;}

    ZeroMemory(pArr, sizeof(int) * nums);
    for (int i = 0; i < nums; ++ i)
    {
        int data = 0;
        cout << "请输入第 "<< i << " 个元素的值:";
        cin >> data;

        pArr[i] = data;
    }

    cout << endl<<"输入完毕"<<endl;



    cout << "请输入哈希表长度:";
    cin >> length;

    

    cout << endl <<endl <<"开始构造哈希表"<<endl;
    CreateHashTable(pHashtable, length, pArr, nums);
    cout <<endl<<"哈希表构造完毕"<<endl<<endl;

    cout<<endl<<endl;
    
    int value = 0;
    for (int i = 0; i < nums * 10; ++ i)
    {
        cout << "请输入要查查找的元素:";
        cin >> value;

        Find(pHashtable, value, value % length);
        cout<<endl;
    }

    return 0;
}