#include <stdio.h>
#include <malloc.h>
#define NULLKEY 0 //0 is no record flag
#define N 10 //Number of data elements
typedef int KeyType;//Let the keyword field be an integer
typedef struct
{
KeyType key;
int ord;
}ElemType; //Data element type
//Open the storage structure of the addressable hash table
int hashsize[]={11,19,29,37}; //Hash table capacity increasing table, an appropriate sequence of prime Numbers
int m=0; //Hash table length, global variable
typedef struct
{
ElemType *elem; //Data elements store base addresses and dynamically allocate arrays
int count; //Current number of data elements
int sizeindex; //Hashsize [sizeindex] is the current capacity
}HashTable;
#define SUCCESS 1
#define UNSUCCESS 0
#define DUPLICATE -1
//Construct an empty hash table
int InitHashTable(HashTable *H)
{
int i;
(*H).count=0; //The current number of elements is 0
(*H).sizeindex=0; //The initial storage capacity is hashsize[0]
m=hashsize[0];
(*H).elem=(ElemType*)malloc(m*sizeof(ElemType));
if(!(*H).elem)
exit(0); //Memory allocation failed
for(i=0;i<m;i++)
(*H).elem[i].key=NULLKEY; //Mark of an unfilled record
return 1;
}
//& have spent Destroy hash table H
void DestroyHashTable(HashTable *H)
{
free((*H).elem);
(*H).elem=NULL;
(*H).count=0;
(*H).sizeindex=0;
}
//A simple hash function (m for table length, global variable)
unsigned Hash(KeyType K)
{
return K%m;
}
//Open addressing handles conflicts
void collision(int *p,int d) //Linear detection and hash
{
*p=(*p+d)%m;
}
//Algorithm 9.17
//Find the element with key code K in the open addressing hash table H. If the search is successful, p indicates the pending data
//Element in the table and returns SUCCESS; Otherwise, p indicates the insertion location and returns UNSUCCESS
//C is used to count the number of conflicts, and its initial value is set to zero for reference when inserting in the table.
int SearchHash(HashTable H,KeyType K,int *p,int *c)
{
*p=Hash(K); //Find the hash address
while(H.elem[*p].key!=NULLKEY&&!(K == H.elem[*p].key))
{
//There are records in this position. And the keywords are not equal
(*c)++;
if(*c<m)
collision(p,*c); //Find the next probe address, p
else
break;
}
if (K == H.elem[*p].key)
return SUCCESS; //Successful search, p returns the location of the data element to be searched
else
return UNSUCCESS; //The search failed (h.lem [p].key==NULLKEY), and p returns the insertion position
}
int InsertHash(HashTable *,ElemType); //Declaration of a function
//Rebuild the hash table
void RecreateHashTable(HashTable *H) //Rebuild the hash table
{
int i,count=(*H).count;
ElemType *p,*elem=(ElemType*)malloc(count*sizeof(ElemType));
p=elem;
printf(" Rebuild the hash table n");
for(i=0;i<m;i++) //Save the original data to elem
if(((*H).elem+i)->key!=NULLKEY) //This unit has data
*p++=*((*H).elem+i);
(*H).count=0;
(*H).sizeindex++; //Increase storage capacity
m=hashsize[(*H).sizeindex];
p=(ElemType*)realloc((*H).elem,m*sizeof(ElemType));
if(!p)
exit(0); //Memory allocation failed
(*H).elem=p;
for(i=0;i<m;i++)
(*H).elem[i].key=NULLKEY; //Flags for unfilled records (initialization)
for(p=elem;p<elem+count;p++) //Insert the original data into the reconstructed hash table according to the new table length
InsertHash(H,*p);
}
//Algorithm 9.18
//If the search fails, insert the data element e into the open addressing hash table H, and return 1;
//If the number of conflicts is too large, the hash table is rebuilt.
int InsertHash(HashTable *H,ElemType e)
{
int c,p;
c=0;
if(SearchHash(*H,e.key,&p,&c)) //There are already elements in the table that have the same keyword as e
return DUPLICATE;
else if(c<hashsize[(*H).sizeindex]/2) //Number of conflicts c does not reach the upper limit,(the threshold of c is adjustable)
{
//Insert the e
(*H).elem[p]=e;
++(*H).count;
return 1;
}
else
RecreateHashTable(H); //Rebuild the hash table
return 0;
}
//The hash table is traversed in the order of hash addresses
void TraverseHash(HashTable H,void(*Vi)(int,ElemType))
{
int i;
printf(" Hash address 0 ~ %dn",m-1);
for(i=0;i<m;i++)
if(H.elem[i].key!=NULLKEY) //There are data
Vi(i,H.elem[i]);
}
//Find the element with key code K in the open addressing hash table H. If the search is successful, p indicates the pending data
//Element in the table and returns SUCCESS; Otherwise, return UNSUCCESS
int Find(HashTable H,KeyType K,int *p)
{
int c=0;
*p=Hash(K); //Find the hash address
while(H.elem[*p].key!=NULLKEY&&!(K == H.elem[*p].key))
{ //There are records in this position. And the keywords are not equal
c++;
if(c<m)
collision(p,c); //Find the next probe address, p
else
return UNSUCCESS; //Invalid search (h.lem [p]. Key ==NULLKEY)
}
if (K == H.elem[*p].key)
return SUCCESS; //Successful search, p returns the location of the data element to be searched
else
return UNSUCCESS; //Invalid search (h.lem [p]. Key ==NULLKEY)
}
void print(int p,ElemType r)
{
printf("address=%d (%d,%d)n",p,r.key,r.ord);
}
int main()
{
ElemType r[N] = {
{17,1},{60,2},{29,3},{38,4},{1,5},
{2,6},{3,7},{4,8},{60,9},{13,10}
};
HashTable h;
int i, j, p;
KeyType k;
InitHashTable(&h);
for(i=0;i<N-1;i++)
{
//Insert the first N-1 records
j=InsertHash(&h,r[i]);
if(j==DUPLICATE)
printf(" The existing keyword in the table is %d Could not insert a record (%d,%d)n",
r[i].key,r[i].key,r[i].ord);
}
printf(" The hash table is traversed in the order of hash addresses :n");
TraverseHash(h,print);
printf(" Please enter the keyword for the record to find : ");
scanf("%d",&k);
j=Find(h,k,&p);
if(j==SUCCESS)
print(p,h.elem[p]);
else
printf(" Did not find n");
j=InsertHash(&h,r[i]); //Insert the NTH record
if(j==0) //Rebuild the hash table
j=InsertHash(&h,r[i]); //Rebuild the hash table After reinserting the first N A record
printf(" Traverse the reconstructed hash table in the order of hash addresses :n");
TraverseHash(h,print);
printf(" Please enter the keyword for the record to find : ");
scanf("%d",&k);
j=Find(h,k,&p);
if(j==SUCCESS)
print(p,h.elem[p]);
else
printf(" Did not find n");
DestroyHashTable(&h);
system("pause");
return 0;
}