#include <iostream>
#include <map>
#include <cmath>
#include <vector>

double euclidean_length(const std::vector<double> &v);
double scalar_product(const std::vector<double> &v, const std::vector<double> &w);
std::vector<double> normalize(const std::vector<double> &v);
double euclidean_distance(const std::vector<double> &v, const std::vector<double> &w);
void print_dvector(const std::vector<double> &v);
unsigned fibonacci_rec(unsigned n);
unsigned fibonacci_nonrec(unsigned n);
void mymap();


int main()
{
    std::vector<double> a = {1, 2, 3};
    std::vector<double> b = {4, 5, 6};
    std::cout << "length of 'a': " << euclidean_length(a) << '\n';
    std::cout << "scalar product of 'a' and 'b': " << scalar_product(a, b) << '\n';
    print_dvector(normalize(a));
    std::cout << "distance between 'a' and 'b': " << euclidean_distance(a, b) << '\n';
    std::cout << "Recursive Fibonacci of 25: " << fibonacci_rec(25) << '\n';
    std::cout << "Fibonacci of 50: " << fibonacci_nonrec(25) << '\n';
    mymap();
}

void print_dvector(const std::vector<double> &v) {
    for (const double &d : v) {
        std::cout << d << '\n';
    }
    std::cout << '\n';
}
double euclidean_length(const std::vector<double> &v)
{
    double sum = 0;

    return std::sqrt(sum);
}

double scalar_product(const std::vector<double> &v, const std::vector<double> &w)
{
    double product = 0;
    if(v.size()!=w.size()) { return std::nan(""); }
    for(int i=0; i<v.size(); ++i)
    {
        product += v[i]*w[i];
    }
    return product;
}

std::vector<double> normalize(const std::vector<double> &v)
{
    double length = euclidean_length(v);
    std::vector<double> norm;
    for(int i=0; i<v.size(); ++i)
    {
        norm.push_back(v[i]/length);
    }
    return norm;
}

double euclidean_distance(const std::vector<double> &v, const std::vector<double> &w)
{
    if(v.size()!=w.size()) { return std::nan(""); }
    double distance = 0;
    for(int i=0; i<v.size(); ++i)
    {
        distance += (v[i]-w[i])*(v[i]-w[i]);
    }
    return std::sqrt(distance);
}

unsigned fibonacci_rec(unsigned n)
{
    if(n<=2)
    {
        return 1l;
    }
    else
    {
        return fibonacci_rec(n-1)+fibonacci_rec(n-2);
    }
}

unsigned fibonacci_nonrec(unsigned n)
{
    unsigned fibo = 0;
    unsigned prev_fibo = 1;
    unsigned prev_prev_fibo = 0;

   for(int i=2; i<=n; ++i)
    {
        fibo = prev_fibo + prev_prev_fibo;
        prev_prev_fibo = prev_fibo;
        prev_fibo = fibo;
    }

    return fibo;
}

void mymap()
{
    std::map<std::string, int> mymap;
    mymap["Peter"] = 40;
    mymap["Brian"] = 4;
    mymap["Stewie"] = 1;
    mymap["Chris"] = 15;
    mymap["Meg"] = 14;

    for(const auto& n : mymap)
    {
        std::cout << n.first << ' ' << n.second << '\n';
    }

    mymap["Lois"] = 41;
    std::cout << '\n';

    for(const auto& n : mymap)
    {
        std::cout << n.first << ' ' << n.second << '\n';
    }
}