改进后的希尔排序，速度快一倍

来源：互联网发布：数据恢复精灵4 注册码编辑：程序博客网时间：2024/05/22 07:00
改进方法参照：http://faculty.simpson.edu/lydia.sinapova/www/cmsc250/LN250_Weiss/L12-ShellSort.htm#increments
/*************************************************************************> File Name: shellsort.cpp> Author:keson > Mail:keson@bupt.edu.cn > Created Time: 2014年11月30日 星期日 10时05分18秒 ************************************************************************/#include<iostream>#include<vector>#include<fstream>#include<string>#include<algorithm>#include<cmath>using namespace std;//一般的希尔排序函数template<typename Comparable>void shellsort(vector<Comparable> &a){    for(int gap=a.size()/2;gap>0;gap/=2)       for(int i=gap;i<a.size();++i)    {        Comparable tmp=std::move(a[i]);        int j=i;        for(;j>=gap&&tmp<a[j-gap];j-=gap)           a[j]=std::move(a[j-gap]);        a[j]=std::move(tmp);    }}//得到希尔排序的序列号: 1,5,19,41,109.......//可参考http://faculty.simpson.edu/lydia.sinapova/www/cmsc250/LN250_Weiss/L12-ShellSort.htm#incrementstemplate<typename Comparable>vector<int>  getseq(const vector<Comparable> &a){    vector<int>  vec;    int val1=0,val2=0;    for(int i=0;val1<a.size()/2&&val2<a.size()/2;i++)    {        val1=9*(pow(4,i)-pow(2,i))+1;        val2=pow(2,i+2)*(pow(2,i+2)-3)+1;        vec.push_back(val1);        vec.push_back(val2);    }    sort(vec.begin(),vec.end(),greater<int>());    return vec;}//用得到的序列号进行希尔排序template<typename Comparable>void shellsort1(vector<Comparable> &a){    vector<int> seq=getseq(a);    int index=0;    for(int gap=seq[index];index<seq.size();gap=seq[++index])    {        for(int i=gap;i<a.size();++i)        {            Comparable tmp=std::move(a[i]);            int j=i;            for(;j>=gap&&tmp<a[j-gap];j-=gap)               a[j]=std::move(a[j-gap]);            a[j]=std::move(tmp);        }            }    }int main(){    ofstream out;    out.open("NUMBER_FILE");    int SIZE=50000000;    while(SIZE)    {        out<<rand()%10000<<" ";        SIZE--;    }        out.close();    ifstream in;    in.open("NUMBER_FILE");    ofstream out2("SORT1");    vector<int>vec;    int val;    while(in>>val)      vec.push_back(val);    vector<int> vec1(vec);    clock_t start_time=clock();    //原来的希尔排序    shellsort(vec);    clock_t end_time=clock();    cout<<"Running time is:"<<    static_cast<double>(end_time-start_time)/CLOCKS_PER_SEC<<" S"<<endl;    clock_t start_time1=clock();        //改进的希尔排序    shellsort1(vec1);    clock_t end_time1=clock();    cout<<"QUICK Running time is "<<    static_cast<double>(end_time1-start_time1)/CLOCKS_PER_SEC<<" S"<<endl;       //测试两种排序结果是否一样    int flag=0;    for(int i=0;i<vec.size();i++)    {                if(vec[i]!=vec1[i])         flag++;    }    cout<<flag<<endl;    for(auto c:vec)      out2<<c<<" ";        in.close();    out2.close();}
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