归并排序—数据结构与算法分析第四版

/*************************************************************************
	> File Name: mergeSort.cpp
	> Author:keson 
	> Mail:[email protected] 
	> Created Time: 2014年12月01日 星期一 21时32分03秒
 ************************************************************************/

#include<iostream>
#include<vector>
#include<fstream>

using namespace std;

template<typename Comparable>
void merge(vector<Comparable> &a,vector<Comparable> &tmpArray,
                  int leftPos,int rightPos,int rightEnd)
{
    int leftEnd=rightPos-1;
    int tmpPos=leftPos;
    int numElements=rightEnd-leftPos+1;

    while(leftPos<=leftEnd&&rightPos<=rightEnd)
         if(a[leftPos]<=a[rightPos])
           tmpArray[tmpPos++]=std::move(a[leftPos++]);
         else
           tmpArray[tmpPos++]=std::move(a[rightPos++]);
    while(leftPos<=leftEnd)    //copy rest of first half
         tmpArray[tmpPos++]=std::move(a[leftPos++]);

    while(rightPos<=rightEnd)   //copy rest of right half
       tmpArray[tmpPos++]=std::move(a[rightPos++]);

    //copy tmpArray back

    for(int i=0;i<numElements;++i,--rightEnd)
       a[rightEnd]=std::move(tmpArray[rightEnd]);
}


/**
 * Internal method that makes recursive calls
 * a is an array of Comparable items
 * tmpArray is an array to place the merged result.
 * left is the left-most index of the subarray.
 * right is the right-most index of the subarray.
 */
template<typename Comparable>
void mergeSort(vector<Comparable> &a,vector<Comparable> &tmpArray,
               int left,int right)
{
    if(left<right)
    {
        int center=(left+right)/2;
        mergeSort(a,tmpArray,left,center);
        mergeSort(a,tmpArray,center+1,right);
        merge(a,tmpArray,left,center+1,right);
    }
}


/**
 * Mergesort algorithm(driver)
 */
template<typename Comparable>
void mergeSort(vector<Comparable> &a)
{
    vector<Comparable> tmpArray(a.size());
    mergeSort(a,tmpArray,0,a.size()-1);
}

int main()
{
    vector<int> vec;
    int val;

    ifstream in;
    in.open("NUMBER_FILE");
    ofstream out;
    out.open("sort_out");
    

    while(in>>val)
       vec.push_back(val);

    clock_t start_time1=clock();  
    mergeSort(vec);
    clock_t end_time1=clock();  
    cout<<"QUICK Running time is "<<  
    static_cast<double>(end_time1-start_time1)/CLOCKS_PER_SEC<<" S"<<endl; 
    cin.clear();
    for(auto c:vec)
       out<<c<<" ";
    cout<<endl;

    out.close();
    in.close();
}