Przykład z zadania z olimpiady informatycznej gimnazjalistów

#include <iostream>
using namespace std;
#include <string>
#include <vector>
#include <algorithm>
#include <iterator>
#include <numeric>
#include <cmath>

//====================================================================================================================

void printVector( const vector < double >& vec )
{
    for( auto it = vec.begin(); it != vec.end(); ++it )
    {
        cout << * it << " ";
    }
    cout << endl;
}

void addLamp( vector < double >& lampPositions, int val );

//====================================================================================================================

int main()
{
   
    int howManyAlready, howmanyToBuy, hallLength;
    vector < double > lampPositions;
   
    cin >> howManyAlready >> howmanyToBuy >> hallLength;
   
    lampPositions.reserve( hallLength );
   
    int readedPos;
   
    for( int i = 0; i < howManyAlready; ++i )
    {
        cin >> readedPos;
        lampPositions.push_back( readedPos );
    }
   
    //printVector(lampPositions);
   
    for( int i = 0; i < howmanyToBuy; ++i )
    {
        addLamp( lampPositions, howmanyToBuy - i );
        //printVector(lampPositions);
    }
   
    decltype( lampPositions ) result( lampPositions.size() );
    adjacent_difference( lampPositions.begin(), lampPositions.end(), result.begin() );
    //printVector(result);
    double minSurface = 0.d;
    minSurface = accumulate( result.begin(), result.end(), minSurface,[]( double & sum, double & current ) { return sum += current * current / 4.d; } );
   
    cout << minSurface << endl;
   
   
   
    return 0;
}
//====================================================================================================================
void addLamp( vector < double >& lampPositions, int val )
{
    vector < double > result( lampPositions.size() );
    adjacent_difference( lampPositions.begin(), lampPositions.end(), result.begin() );
   
    auto wherePutLamp = distance( result.begin(), max_element( result.begin(), result.end() ) );
   
    lampPositions.insert( lampPositions.begin() + wherePutLamp, lampPositions[ wherePutLamp - 1 ] +( lampPositions[ wherePutLamp ] - lampPositions[ wherePutLamp - 1 ] ) / static_cast < double >( val == 1 ? 2
        : val ) );
}
//*****************************************************************************
[ cpp ]

Tylko mam pro ś b ę, ż eby ś go sprawdzi ł czy rzeczywi ś cie ź le dzia ł a i tylko mia ł em szcz ę ś cie do danych testowych.