8)排序④排序算法之归并排序

#include "iostream"
#include "vector"
#include "time.h"
#include "iomanip"
using namespace std;

#define num 25
typedef int type;//type类型为int

/*
*将非降数组A,B,中的元素
*/
void merge(vector<type>A,vector<type>B,vector<type>&C,int flags)
{
    int ia =0,ib=0,ic=0;
    if(flags==1)//升序
    {
        while(ia<A.size()&&ib<B.size())
        {
            if(A[ia]<=B[ib])
            {
                C.push_back(A[ia++]);
            }else C.push_back(B[ib++]);
        }
    }else if(flags==0){//降序
        while(ia<A.size()&&ib<B.size())
        {
            if(A[ia]>=B[ib])
            {
                C.push_back(A[ia++]);
            }else C.push_back(B[ib++]);
        }
    }
    while(ia<A.size())
    {
        C.push_back(A[ia++]);
    }

    while(ib<B.size())
    {
        C.push_back(B[ib++]);
    }
    
}

/*
*将n个长度的子表归并为m个子表（n为偶数，m=n/2;否,m=n/2+1）
*/
int Merge_sort(vector<vector<int>>array,int n,vector<vector<int>>&mid,int &count,int flags)
{
    int i;
    if(n%2==0)
    {
        count = n/2;
        for(i=0;i<n-1;i=i+2)
        {
            merge(array[i],array[i+1],mid[i/2],flags);
        }
    }else{
        count = n/2 +1;
        vector<int>temp;
        temp.clear();
        for(i=0;i<n-2;i=i+2)
        {
            merge(array[i],array[i+1],mid[i/2],flags);
        }
        merge(array[n-1],temp,mid[count-1],flags);
    }
    return 0;
}

void Sort_Merge()
{
    int i,j,flags;
    time_t start,end;
    vector<int>array;
    cout<<"Initialize Array:"<<endl;
    for(i=0;i<num;i++)//随机产生数组中的数据
    {
        array.push_back(rand()%1000);
        cout<<setw(5)<<array[i]<<" ";
        if((i+1)%10==0)cout<<endl;
    }
    cout<<endl;
    cout<<"please inout flags[flags:1,升序;0降序]:";
    cin>>flags;
    start = clock();
    vector<vector<int>>arraymid(array.size());
    for(i=0;i<array.size();i++)//初始化num个子表
    {
        arraymid[i].push_back(array[i]);
    }
    vector<vector<int>>mid(num);//存放num个子表归并后的子表
    int count =arraymid.size();//用于记录起始子表数目
    int countmid = count;//用于记录归并后子表的数目
    while(count!=1)
    {
        for(i=0;i<countmid;i++)
        {
            mid[i].clear();//清空待存放归并后子表的数组
        }
        Merge_sort(arraymid,count,mid,countmid,flags);//归并

        for(i=0;i<count;i++)//将归并后的子表赋给arraymid,然后继续归并
        {
            arraymid[i].clear();
            for(j=0;j<mid[i].size();j++)
            {
                arraymid[i].push_back(mid[i][j]);
            }
        }
        count = countmid;//子表数目更新为归并后的子表数目
    }
    end = clock();
    cout<<"The Merge_Sorted Array:"<<endl;
    //输出最终排序后的的结果
    for(i=0;i<count;i++)
    {
        for(j=0;j<mid[i].size();j++)
        {
            cout<<setw(5)<<mid[i][j]<<" ";
            if((j+1)%10==0)cout<<endl;
        }
    }
    cout<<endl;

    cout<<"performnace time:";
    cout<<(double)(end - start )/1000<<"Seconds"<<endl;
}

int main()
{
    Sort_Merge();
    return 0;
}