散列的冲突解决方法之分离链接法

分离链接法（separate chaining）：将散列到同一个值的所有元素保留到一个表中（用指针实现的单链表）。

/* 实现分离链接法所需要的类型声明 */



#ifndef _HashSep_H

#define _HahsSep_H



struct ListNode;

typedef struct ListNode *Position;

struct HashTbl;

typedef struct HashTbl *HashTable;



HashTable InitializeTable( int TableSize );

void DestroyTable( HashTable H );

Position Find( ElementType Key, HashTable H );

void Insert( ElementType Key, HashTable H );

ElementType Retrieve( Position P );

/* Routines such as Delete and MakeEmpty are omitted */



#endif     /* _HashSep_H */





/* Place in the implementation file */

struct ListNode

{

    ElementType Element;

    Position    Next;

};



typedef Position List;



/* List *TheList will be an array of lists, allocated later */

/* The lists use headers(for simplicity */

/* though this wastes space */

struct HashTbl

{

    int TableSize;

    List *TheLists;

};

/* 分离链接散列表的初始化例程 */



HashTable

InitializeTable( int TableSize )

{

    HashTable H;

    int i;

    

    if( TableSize < MinTableSize )

    {

        Error( "Table size too small" );

        return NULL;

    }

    

    /* Allocate table */

    H = malloc( sizeof( struct HashTbl ));

    if( H == NULL )

        FatalError( "Out of space!!!" );

    

    H->TableSize = NextPirme( TableSize );

    

    /* Allocate array of lists */

    H->TheLists = malloc( sizeof( List ) * H->TableSize );

    if( H->Thelists == NULL )

        FatalError( "Out of space!!!" );

    

    /* Allocate list headers */

    for( i = 0; i < H->TableSize; i++)

    {

        H->TheLists[ i ] = malloc( sizeof( struct ListNode ) );

        if( H->TheLists[ i ] == NULL)

            FatalError( "Out of space!!!" );

        else 

            H->TheLists[ i ]->Next = NULL;

    }



    return H;

}

/* 分离链接散列表的Find例程 */



Position

Find( ElementType Key, HashTable H )

{

    Position P;

    List L;

    

    L = H->TheLists[ Hash( Key, H->TableSize ) ];

    P = L->Next;

    while( P != NULL && P->Element != Key )        /* Probably need strcmp!! */

        P = P->Next;



    return P;

}

/* 分离链接散列表的Insert例程 */



void

Insert( ElementType Key, HashTable H )

{

    Position Pos, NewCell;

    List L;

    

    Pos = Find( Key, H );

    if( Pos == NULL )    /* Key is not found */

    {

        NewCell = malloc( sizeof( struct ListNode ) );

        if( NewCell == NULL )

            FatalError( "Out of space!!!" );

        else

        {

            L = H->TheLists[ Hash( Key, H->TableSize ) ];

            NewCell->Next = L->Next;

            NewCell->Element = Key;    /* Probably need strcpy ! */

            L->Next = NewCell;

        }

    }

}