// Compare the execution times of inserting at the front vs. inserting
// at the back of a vector.
//
// Usage:
//    ./<exec name> <size of list>

#include <iostream>
#include <vector>
#include <cstdlib>
#include <algorithm>
using namespace std;


void insertManyFront(vector<int> & v, int size) {
	for (int i = 0; i < size; i++) 
    	v.insert(v.begin(), rand() % size);
}

void insertManyBack(vector<int> & v, int size) {
	for (int i = 0; i < size; i++) 
    	v.push_back(rand() % size);
}

int main(int argc, char *argv[]) {
  
  if (argc < 2) { 
  	cout << "Usage: " << argv[0] << " <size> \n"; 
    exit(1);
  }
  int size = atoi(argv[1]);
  
  vector<int> v,w;
  
  // initialize the random seed
  srand(time(NULL));
  
  
  double elapsed_secs;

  // measure time to insert many elements in front
  clock_t begin = clock();
	insertManyFront(v, size);
  clock_t end = clock();

  elapsed_secs = static_cast<double>(end - begin) / CLOCKS_PER_SEC;
  cout << "\nInsert at front elapsed: " << elapsed_secs << " seconds\n";
  
  // measure time to insert many elements in the back
  begin = clock();
  insertManyBack(w, size);
  end = clock();

  elapsed_secs = static_cast<double>(end - begin) / CLOCKS_PER_SEC;
  cout << "Insert back elapsed: " << elapsed_secs << " seconds\n\n";
  
  return 0;
}