#include <iostream>
#include <cmath>
#include <cstring>
#include <cstdlib>
#include <ctime>

void underscore(char* a,size_t size)
{
    for(size_t i = 0; i < size; i++)
    {
    //if 0-48,57-65,90-97,122-255
    if(a[i]>0 && a[i]<48 || a[i]>57 && a[i]<65 || a[i]>90 && a[i]<97 || a[i]>122 && a[i]<255)
    {
        a[i] = 95;
    }
    }
}

double factorial(int n)
{
  return (n == 1 || n == 0) ? 1 : factorial(n - 1) * n;
}


float sinapp(int x,int prec)
{
    float sinv = 0;
    for(int i = 0; i < 10; i++)
    {
        sinv = sinv + (pow((-1),i)*pow(x,(2*i+1)))/(factorial(2*i+1));
    }



    return sinv;
}

float cosapp(int x,int prec)
{
    float cosv=0;
    for(int i = 0; i < 10; i++)
    {
        cosv = cosv + (pow(-1,i)*pow(x,(2*(i))))/(factorial(2*i));
    }



    return cosv;
}

double poly(int* coef, int n, int x)
{
    double result=0;

    for(int i = 0;i<n;i++)
    {
        result = result + coef[i]*pow(x,(n-i-1));
    }
    return result;
}


float meanfunk(int* arr, int n)
{
    float sum = 0;
    for(int i = 0; i< n; i++)
    {
        sum = sum + arr[i];
    }


    return sum/n;
}

int main()
{
    int size, a, b, c;
    char choice=97,text[100];
    srand(time(nullptr));
    //std::cout<<"";

    //task 0
    while(choice != 'x')
    {
        std::cout<<"Select task:"<<std::endl
                 <<"1. Underscore"<<std::endl
                 <<"2. Sin Cos"<<std::endl
                 <<"3. Poly"<<std::endl
                 <<"4. Random mean"<<std::endl
                 <<"x. Exit"<<std::endl;
        std::cin>>choice;

        switch(choice)
        {
        case '1':
        {
        std::cout<<"Please input a text string up to 100 chars"<<std::endl;
        std::cin.ignore();
        std::cin.getline(text,100);
        size = static_cast<size_t>(strlen(text));
        underscore(text,size);
        std::cout<<text<<std::endl;
        break;
        }
        case '2':
        {
        std::cout<<"input the fucking variable or i'll kill your family (maybe) =)..."<<std::endl;
        std::cin>>a;
        std::cout<<"input the fucking precision or i'll kill your family (maybe) =)..."<<std::endl;
        std::cin>>b;
        std::cout<<"sin is: "<<sinapp(a,b)<<std::endl
                 <<"cos is: "<<cosapp(a,b)<<std::endl;

        break;
        }
        case '3':
        {
            // f(x) = -3x^3 + 2x^2 – 3x + 5 // f(2) = - 17
            std::cout<<"input the fucking amount of coefiaghtjyku or i'll kill your family (maybe) =)..."<<std::endl;
            std::cin>>a;
            std::cout<<"input the fucking x or i'll kill your family (maybe) =)..."<<std::endl;
            std::cin>>b;
            int coefs[a];
            for (int i=0; i<a;i++)
            {
                std::cout<<"ILL STAB YOU IF YOU DONT INPUT COEF "<<i<<std::endl;
                std::cin>>coefs[i];
            }
            std::cout<<poly(coefs, a, b)<<std::endl;

        break;
        }
        case '4':
        {
        int b[100];
        std::cout<<"<3"<<std::endl;
        for(int i = 0; i< 100; i++)
        {
        b[i] = rand() % 100 + 50;
        }
        std::cout<<meanfunk(b,100)<<std::endl;
        break;
        }
        case 'x' or 'X':
        {
        return 0;
        break;
        }
        }
    }
    return 0;
}