散列查找的查找插入及冲突处理方法

#include <stdio.h>
#include <math.h>
#include <stdlib.h>

#define MAXTABLESIZE 100000 //最大散列表长度
typedef int ElementType;   //关键词类型
typedef int Index;  //散列地址类型
typedef Index Position; //数据所在位置
//散列单元状态类型，分别对应：有合法元素、空单元、有已删除元素
typedef enum{Legitimate, Empty, Deleted} EntryType;

typedef struct HashEntry Cell;  //散列表单元类型
struct HashEntry
{
    ElementType Data;
    EntryType info;
};

typedef struct TblNode *HashTable; //散列表类型
struct TblNode
{
    int TableSize;
    Cell *Cells;
};

int NextPrime(int N) //返回大于N且不超过MAXTABLESIZE的最小素数
{
    int i, p = (N % 2) ? N+2 : N+1; //从大于N的下一个奇数开始

    while (p <= MAXTABLESIZE) {
        for (i = (int)sqrt(p); i > 2; i--)  //p已经是奇数
            if (!(p % i)) break;   //p不是素数
        if (i == 2) break;  //for正常结束，说明p是素数
        else p += 2;
    }
    return p;
}

HashTable CreatTable(int TableSize)
{
    HashTable H;
    int i;
    H = (HashTable)malloc(sizeof(struct TblNode));
    H->TableSize = NextPrime(TableSize);  //保证散列表最大长度是素数
    H->Cells = (Cell *)malloc(H->TableSize * sizeof(Cell));
    //初始化单元状态为空单元
    for (i = 0; i < H->TableSize; i++)
        H->Cells[i].Info = Empty;
    return H;
}

Position Find(HashTable H, ElementType Key)
{
    Position CurrentPos, NewPos;
    int CNum = 0; //记录冲突次数

    NewPos = CurrentPos = Hash(Key, H->TableSize); //初始散列位置
    while (H->Cells[NewPos].Info != Empty && H->Cells[NewPos].Data != Key)
    {
        //字符串类型的关键词需要strcmp函数
        //统计一次冲突，判断奇偶性
        if (++CNum%2) //奇数次冲突
        {
            NewPos = CurrentPos + (CNum+1)*(CNum+1)/4; //增量为+[(CNum+1)/2]^2
            if (NewPos >= H->TableSize)
                NewPos %= H->TableSize;
        }
        else {  //偶数次冲突
            NewPos = CurrentPos - CNum*CNum/4;   //增量为-(CNum/2)^2
            while (NewPos < 0)
                NewPos += H->TableSize;
        }
    }
    return NewPos;   //此时NewPos是Key的位置或者是一个空位置(没找到)
}

bool Insert(HashTable H, ElementType)
{
    Position Pos = Find(H, Key);
    if (H->Cells[Pos].Info != Legitimate) {
        H->Cells[Pos].Info = Legitimate;
        H->Cells[Pos].Data = Key;
        //字符串类型关键词需要strcpy函数
        return true;
    }
    else {
        printf("键值已存在");
        return false;
    }
}

#include <stdlib.h>
#include <string>
#define KEYLENTH 15 //关键词字符串的最大长度
typedef char ElementType[KEYLENTH+1]; //关键词类型用字符串
typedef int Index;   //散列地址类型
//单链表定义
typedef struct LNode *PtrToLNode;
struct LNode
{
    ElementType Data;
    PtrToLNode Next;
};
typedef PtrToLNode Position;
typedef PtrToLNode List;
//以上是单链表定义

typedef struct TblNode *HashTable;  //散列表类型
struct TblNode       //散列表结点定义
{
    int TableSize;
    List Heads;    //指向链表头结点的数组
};

HashTable CreatTable (int TableSize)
{
    HashTable H;
    int i;
    
    H = (HashTable)malloc(sizeof(struct TblNode));
    H->TableSize = NextPrime(TableSize);
    H->Heads = (List)malloc(H->TableSize*sizeof(struct LNode));
    //初始化表头结点
    for (i = 0; i < H->TableSize; i++) {
        H->Heads[i].Data[0] = ‘\0‘;
        H->Heads[i].Next = NULL;
    }
    return H;
}

Position Find(HashTable H, ElementType Key)
{
    Position P;
    Index Pos;
    
    Pos = Hash(Key, H->TableSize);
    P = H->Heads[Pos].Next;  //从该链表的第一个结点
    //当未到末尾，并且Key未找到时
    while (P && strcmp(P->Data, Key))
        P = P->Next;
    
    return P;
}

bool Insert(HashTable H, ElementType Key)
{
    Position P, NewCell;
    Index Pos;
    
    P = Find(H, Key);
    if (!P) {
        NewCell = (Position)malloc(sizeof(struct LNode));
        strcmp(NewCell->Data, Key);
        Pos = Hash(Key, H->TableSize);
        //将NewCell插入为H->Heads[Pos]链表的第一个结点
        NewCell->Next = H->Heads[Pos].Next;
        H->Heads[Pos].Next = NewCell;
        return true;
    }
    else {
        printf("键值已存在");
        return false;
    }
}

void DestroyTable(HashTable H)
{
    int i;
    Position P, Tmp;
    //释放每个链表的结点
    for (i = 0; i < H->TableSize; i++) {
        P = H->Heads[i].Next;
        while (P) {
            Tmp = P->Next;
            free(P);
            P = Tmp;
        }
    }
    free(H->Heads);
    free(H);
}