算法：分离链表法散列表

Posted 2020-09-07 jmst

hash.h

#ifndef _HASHTABLE_H
#define _HASHTABLE_H

#define MinSize 10

struct ListNode;
struct HashNode;
typedef unsigned int Index;
typedef char *ElementType;
typedef struct ListNode *Position;
typedef struct HashNode *HashTable;


HashTable InitializeHashTable(int TableSize);
Position Find(ElementType key,HashTable H);
void Insert(ElementType key,HashTable H);
void Delete(ElementType key,HashTable H);

#endif

struct ListNode
{
    ElementType key;
    Position next;
};
typedef Position List;

struct HashNode
{
    int TableSize;
    List *TheLists;
};

Hash.c

#include <stdlib.h>
#include <stdio.h>
#include "Hash.h"

//获取下一个素数
static int NextPrime(int N)
{
    int i;
    if(N%2==0)
        N++;
    for(;;N+=2){
        for(i=3;i*i<=N;i+=2){
            if(N%i==0){
                goto ContOuter;
            }
        }
        return N;
        ContOuter:;
    }
    return N;
}
//Hash函数
Index Hash(const char *key,int TableSize)
{
    unsigned int HashVal=0;
    while(*key!=‘\0‘){
        HashVal=(HashVal<<5)+*key++;
    }
    return HashVal%TableSize;
}
HashTable InitializeHashTable(int TableSize)
{
    HashTable H;
    int i;
    H=(HashTable)malloc(sizeof(struct HashNode));
    if(H==NULL){
        printf("out 0f space");
        return NULL;
    }
    H->TableSize=NextPrime(TableSize);
    //分配链表数组空间
    H->TheLists=malloc(sizeof(struct List))*H->TableSize
    if(H->TheLists==NULL){
        printf("out of space");
        return NULL;
    } 
    //分配链表表头空间 
    for(i=0;i<H->TableSize;++i){
        H->TheLists[i]=malloc(sizeof(struct ListNode));
        if(H->TheLists[i]==NULL){
            printf("out of space");
            return NULL;
        }
        H->TheLists[i]->next=NULL;
    }
    return H;
}
Position Find(ElementType key,HashTable H)
{
    Position P;
    List L;
    L=H->TheLists[Hash(key,H->TableSize)];
    P=L->next;
    while(P!=NULL&&strcmp(P->key,key)!=0){
        P=P->next;
    }
    return P;
}
void Insert(ElementType key,HashTable H)
{
    Position Pos,NewCell;
    List L;
    Pos=Find(key,H);
    if(Pos==NULL){
        NewCell=malloc(sizeof(struct ListNode));
        if(NewCell==NULL){
            printf("out of space");
            return NULL;
        }
        L=H->TheLists[Hash(key,H->TableSize)];
        NewCell->next=L->next;
        NewCell->key=malloc(strlen(key))+1;
        strcpy(NewCell->key,key);
        NewCell->key[strlen(key)]=‘\0‘;
        L->next=NewCell;
    }
}
void Delete(EelmentType key,HashTable H)
{
    Position Pos,Pre;
    List L;
    Pos=Find(key,H);
    L=H->TheLists[Hash(key,H->TableSize)];
    for(Pre=L;Pre!=NULL;Pre=Pre->next){
        if(Pre->next==Pos){
            Pre->next=Pos->next;
            free(Pos->key);
            free(Pos);
            break;
        }
    }
}
void DestoryTable(HashTable H)
{
    Position P,Tmp;
    int i;
    for(i=0;i<H->TableSize;++i){
        P=H->TheLists[i];
        while(P!=NULL){
            Tmp=P->next;
            free(P->key);
            free(P);
            P=Tmp;
        }
    }
    free(H);
}