Question

c++ program

Functions or classes are ok.

Please read data into program from descending_mostly_sorted.txt and store into an array.

Implement Selection Sort to sort the values in ascending order. Least → Greatest

Measure the time it takes to execute the sort in milliseconds or even nanoseconds.

Please run the sort 3 times.

• Attach Photos of Source Code and Output

Answer 1

The c++ code for your program is as. Make sure you have a text file filled with lots and lots of numbers one number in a line. Below i will attach the python script too which will generate this txt file for you.After that use proper path of that txt file in the c++ program.

****************************myProg.cpp***************************

//============================================================================
// Name : SelectionSortTime.cpp
// Author :
// Version :
// Copyright : Your copyright notice
// Description : Hello World in C++, Ansi-style
//============================================================================

#include <iostream>
#include <fstream>
#include <chrono>
using namespace std;
using namespace std::chrono;
void selectionSort(int arr[],int size){
   int index,temp;
   for (int i = 0; i < size-1; i++)
   {
   index = i;
   for (int j = i+1; j < size; j++) {
   if (arr[j] < arr[index]) {
   index = j;
   }
   }

   temp=arr[index];
   arr[index]=arr[i];
   arr[i]=temp;

   }
}

int main() {

   int arr[50000];
   int i=0;
      ifstream file("descending_mostly_sorted.txt");
      if(!file){
          cout<<"File not found"<<endl;
          return 0;
      }
   string str;
   while (getline(file, str))
   {
       //cout<<str<<endl;
       arr[i]=stoi(str);
       i++;
   }

   auto start = high_resolution_clock::now();
   selectionSort(arr,i);
   auto stop = high_resolution_clock::now();
   auto duration = duration_cast<milliseconds>(stop - start);

   cout<<"\nSorting descending array took "<<duration.count()<<" milliseconds"<<endl;

   auto start2 = high_resolution_clock::now();
   selectionSort(arr,i);
   auto stop2 = high_resolution_clock::now();
   auto duration2 = duration_cast<milliseconds>(stop2 - start2);

   //best case time complexity is almost same for selection sort as worst case
   cout<<"\nSorting sorted array took "<<duration2.count()<<" milliseconds"<<endl;
   //output sorted numbers to another file
   ofstream f;
       f.open("ascending.txt");
       f<<"sorted numbers\n";

       for(int j=0;j<i;j++){
           f<<arr[j]<<"\n";
       }
   return 0;
}

The text file looks like this: