开放地址法散列表ADT

数据结构定义如下：

typedef unsigned int Index;
typedef Index 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, HashTable H);
HashTable Rehash(HashTable H);

enum KindOfEntry {Legitimate, Empty, Deleted};
struct HashEntry{
    ElementType Element;
    enum KindOfEntry Info;
};
typedef struct HashEntry Cell;

struct HashTbl{
    int TableSize;
    Cell *TheCells;
};

初始化函数代码如下：

HashTable InitializeTable(int TableSize){
    HashTable H;
    int i;

    if(TableSize < MinTableSize){
        printf("Table size too small
");
        return NULL;
    }

    H = malloc(sizeof(struct HashTbl));
    H->TableSize = NextPrime(TableSize);
    H->TheCells = malloc(H->TableSize * sizeof(Cell));

    for(i=0; i<H->TableSize; i++)
        H->TheCells[i].Info = Empty;
    
    return H;
}

Find函数实现代码如下：

Position Find(ElementType Key, HashTable H){
    Position Pos;
    int i;

    i=0;
    Pos = Hash(Key, H->TableSize);
    while(H->TheCells[Pos].Info != Empty 
        && H->TheCells[Pos].Element != Key){
            Pos += (++i)*2-1;
            if(Pos >= H->TableSize)
                Pos -= H->TableSize;
    }
    return Pos;
}

Insert函数代码实现如下：

void Insert(ElementType Key, HashTable H){
    Position Pos;
    Pos = Find(Key, H);
    if(H->TheCells[Pos].Info != Legitimate){
        H->TheCells[Pos].Info = Legitimate;
        H->TheCells[Pos].Element = Key;
    }
}

Rehash函数代码实现如下：

HashTable rehash(HashTable H){
    int i, OldSize = H->TableSize;
    HashTable OldH = H;
    Cell *OldCells = H->TheCells;
    

    H = InitializeTable(2*OldSize);
    for(int i=0; i<OldSize; i++){
        if(OldCells[i].Info == Legitimate)
            Insert(OldCells[i].Element, H);
    }

    free(OldH);
    free(OldCells);
    return H;
}