几种常用查找算法

几种常用查找算法（顺序查找法、二分法、二叉树、哈希表法）的比较// 临时工作区.cpp : Defines the entry point for the console application.//2008.9.8 数据结构课程设计第一至二题#include<iostream>#include<stdlib.h>#include<time.h>using namespace std;template<class T>int Find_s(T data[], int n,T key,int &icmp)//顺序查找(从n维数组中查找key,并且给出比较的次数icmp{icmp=0;for(int i=0;i<n;i++){   icmp++;   if(data[i]==key)    return i;}   return -1;}template<class T>int Find_t(T data[], int n,T key,int &icmp)//二分查找(从n维数组中查找key,并且给出比较的次数icmp{int i=0,j=n-1;icmp=0;while(data[(i+j)/2]!=key&&i<=j){   icmp++;   if(data[(i+j)/2]>key)    j=(i+j)/2-1;   else    i=(i+j)/2+1;}if(i>j)   return -1;return (i+j)/2;}///以下是二叉查找树查找法template<class T>class BintreeNode{public:T data;BintreeNode* left;BintreeNode*right;BintreeNode():left(0),right(NULL){}BintreeNode(T item):data(item),left(NULL),right(NULL){}~BintreeNode(){   if(left!=0)    delete left;   if(right!=0)    delete right;}};template<class T>class Bintree{public:int num;BintreeNode<T>* root;BintreeNode<T>* Find_bt(T key,int &icmp,int itype=0)//一个二叉树查找算法，itype=1时有插入功能（不同的值时）{   icmp=0;   if(root==0)   {    icmp++;    if(itype==0)     return NULL;    else    {     num++;     return root=new BintreeNode<T>(key);    }   }   else   {    BintreeNode<T>* ptr=root,*p;    while(ptr!=NULL)    {     icmp++;     p=ptr;     if(ptr->data==key)      return ptr;     else     {      if(ptr->data>key)       ptr=ptr->left;      else       ptr=ptr->right;     }    }    if(itype)    {     num++;     if(p->data>key)      return p->left=new BintreeNode<T>(key);     else      return p->right=new (BintreeNode<T>)(key);    }    return NULL;   }//else}//Find_btBintree():root(0),num(0){}~Bintree(){delete root;}};int compare(const void* a,const void* b){return *(int *)a-*(int *)b;}template<class T>class Link{public:T data;Link<T>* next;Link<T>():next(0){}Link<T>(T item):data(item),next(0){}~Link<T>(){if(next) delete next;}};template<class T>class LinkList{public:Link<T>* first;LinkList<T>():first(0){}~LinkList<T>(){if(first)delete first;}Link<T>* Find_hash(T key,int &icmp,int ntype=0)//查找与插入,当ntype=1时为插入{   icmp=0;   if(first==0)   {    icmp++;    if(ntype)     return first=new Link<T>(key);    else      return NULL;   }   else   {    Link<T>*ptr=first,*p;    while(ptr!=NULL)    {     icmp++;     p=ptr;     if(ptr->data==key)      return ptr;     ptr=ptr->next;    }    if(ntype)     return p->next=new Link<T>(key);    return NULL;   }}};template<class T>class Hash{public:LinkList<T>* hashlist;int size;Hash<T>(int n=113):size(n){   hashlist=new LinkList<T>[n];}~Hash<T>(){delete []hashlist;}void init_hash(T data[],int n)//初始化哈希查找表-----拉链法冲突调节{   int t;   for(int i=0;i<n;i++)   {    int pos=data[i]%size;    hashlist[pos].Find_hash(data[i],t,1);   }}Link<T>* Find_hash(T key,int &icmp)//查找关键词   采用除法杂凑函数{   int pos=key%size;   return hashlist[pos].Find_hash(key,icmp);}};int main(){srand(time(0));do{int n=rand()%100000+1000;int *a=new int[n];for(int i=0;i<n;i++)   a[i]=rand()%100000;int key=rand()%n;int icmp;int j=Find_s(a,n,key,icmp);//使用顺序查找法查找key值的位置cout<<"数据总数:"<<n<<"\t查找关健字key:"<<key<<   "\t查找比较次数:icmp\n顺序查找法：\npos:"   <<j<<"\tdata:"<<a[j]<<"   icmp:"<<icmp<<endl;Bintree<int> btree;for(i=0;i<n;i++)   btree.Find_bt(a[i],icmp,1);//未排序之前插入到二叉查找树中qsort(a,n,sizeof(int),compare);//对数组进行升序排序cout<<"二分查找法："<<endl;cout<<"pos:"<<Find_t(a,n,key,icmp)<<"\ticmp:";//使用二分查找法查找key值的位置cout<<icmp<<endl;cout<<"二叉查找树："<<endl;cout<<"data:"<<(btree.Find_bt(key,icmp)==NULL?-1:btree.Find_bt(key,icmp)->data );cout<<"\ticmp:"<<icmp<<endl;//"\tnum:"<<btree.num<<endl;Hash<int > hash(1000);hash.init_hash(a,n);cout<<"哈希表查找："<<endl;cout<<"data:"<<((hash.Find_hash(key,icmp)==NULL)?-1:(hash.Find_hash(key,icmp))->data);cout<<"\ticmp:"<<icmp<<endl;}while(getchar()-'0');//直到输入为'0'时结束，一直按Enter可以继续进行运算return 0; }