选择排序

Posted 2020-09-07 每天一点积累

选择排序思路在于选择

先认为第一个数是最大值

将当前最大值序号存在一个变量中

将剩下的数依次与最大值比较

比较到最后将最大值序号指向数与当前第一个数交换

#include <iostream>
#include <sstream>
using namespace std;
template<typename T> 
void  selection_sort    (T * array, int len,bool ascending)
{

        T tmp = 0;
        int pos = 0;
        if(ascending)
        {
            for(int i = 0; i < len-1; i ++)
            {
                pos = i;    
                for(int j = i + 1; j < len; j++)
                {
                    if(array[j]>array[pos])
                        pos = j;
                }
                if(pos!=i)
                {
                tmp = array[i];
                array[i] = array[pos];
                array[pos] = tmp;    
                }
            }
        }
        else
        {
            for(int i = 0; i < len-1; i ++)
            {
                pos = i;    
                for(int j = i + 1; j < len; j++)
                {
                    if(array[j]<array[pos])
                        pos = j;
                }
                if(pos!=i)
                {
                tmp = array[i];
                array[i] = array[pos];
                array[pos] = tmp;    
                }
            }
        }

}


int main(int arc,char** argv)
{
    if(arc<2)
    {
    cerr<<"argument is not enough"<<endl;
    return 1;
    }
    string str = argv[1];
    stringstream ss;
    ss <<str;
    int number;
    ss >> number;
    
    cout << "number:" << number <<endl;
    
     float * data = new float[number];
    for(int i = 0; i<number;i++)
    cin>>data[i];

    cout<<"data"<<endl;

    for(int i = 0; i<number;i++)
    cout<<data[i]<<endl;

    selection_sort<float>(data,number,true);

    cout<<"sorted data"<<endl;
    for(int i = 0; i<number;i++)
    cout<<data[i]<<endl;
    
    delete [] data;
  return 0;
}