#include <iostream>

#include <vector>

#include <random>

template <typename Iterator>

void print_range( Iterator begin, Iterator end )

{

std::cout << "{ ";

for( auto it = begin; it != end; ++it )

{

std::cout << *it;

if( it + 1 != end )

{

std::cout << ",";

}

std::cout << " ";

}

std::cout << "}" << std::endl;

}

float add( std::vector<float> *vec, int i, float y )

{

(*vec)[i] += y;

return (*vec)[i];

}

float partial_sum( std::vector<float> *vec, int i )

{

float result = 0.0;

for( int j = 0; j < i; ++j )

{

result += (*vec)[i];

}

return result;

}

int main( int argv, char *argc[] )

{

std::random_device rd;

std::mt19937 gen( rd() );

std::vector<float> data;

for( int i = 0; i < 20; ++i )

{

data.push_back( (float) i / 2.0 );

}

std::shuffle( data.begin(), data.end(), gen );

print_range( data.begin(), data.end() );

std::cout << add( &data, 3, 2.3 ) << std::endl;

print_range( data.begin(), data.end() );

std::cout << partial_sum( &data, 5 );

}