Alina's Lab

//#include "stdafx.h"
//#include <conio.h>
#include <cmath>
#include <clocale>
#include <iostream>
#include <functional>
double count_n(const std::pair<std::int32_t,std::int32_t>& preconditions,std::size_t n, const std::function<double(double b, double c)>& relax){
    double result, a = preconditions.first, b = preconditions.second;
    if (n < 3){ return (n == 1? a:b); }
    for(int i = 3; i <= n; i++){
        result = relax(a, b);
        a = b; b = result;
    }
    return result;
}
double relax_23(double b, double c){ return sin(c) + 10*b; }
double relax_24(double b, double c){ return sqrt(c) + sqrt(b); }
double relax_25(double b, double c){ return sqrt(c+10) + (b+2)*(b+2); }
double relax_26(double b, double c){ return (c+b)/10; }
double relax_27(double b, double c){ return (c+10)*b; }
double relax_28(double b, double c){ return (c*b)/10; }

int main(int argc, char* argv[]){
    std::size_t task_number, number_index;
    std::function<double(double b, double c)> relax_function;
    std::pair<std::int32_t,std::int32_t> preconditions;
    //std::setlocale(LC_ALL,"Russian")
    while(true){
        std::cout << "Введите номер последовательности:>";
        std::cin >> task_number;
        std::cout << "Введите номер числа в последовательности:>";
        std::cin >> number_index;
        switch (task_number) {
            case 23:
                relax_function = relax_23;
                preconditions = {0,1};
                break;
            case 24:
                relax_function = relax_24;
                preconditions = {0,1};
                break;
            case 25:
                relax_function = relax_25;
                preconditions = {0,1};
                break;
            case 26:
                relax_function = relax_26;
                preconditions = {0,1};
                break;
            case 27:
                relax_function = relax_27;
                preconditions = {10,1};
                break;
            case 28:
                relax_function = relax_28;
                preconditions = {1,2};
                break;
            default:
                std::cout << "Неверный номер последовательности.\n";
                return 0;
        }
        printf("В последовательности %lu число под номером %lu = %f\n",task_number,number_index, count_n(preconditions,number_index,relax_function));
    }
    //getch();
    return 0;
}