algebra4

// algebra4.cpp
//
#include <iostream>
#include <string>
using namespace std;

const int n = 11;
const int p = 257;
const int len = 46;

int a, b, x, z0, z1;
int shifr[3][len + 1], aa;
string s;
int mas[len + 2];

int factor(int x, int i, int p);
int factorial(int x, int i, int p);
int f3(int t, int p);

int main()
{
    cout << "algebra4.cpp" << endl;
    s = "Undergraduate of Polotsk State University 2020";

    s += string(len - s.length(), ' '); // наращиваем строку до len

    for (int i = 0; i < len; i++)
    {
        mas[i] = s[i];
        cout << s[i] << "\t" << mas[i] << endl;
    }

    for (int j = 0; j < len; j++)
    {
        x = mas[j];
        a = 1, aa = 2;
        for (int i = 1; i <= n - 1; i++)
        {
            z0 = factor(x, i, p);
            a = (a + z0) % p;
        }
        shifr[0][j] = a;
        b = 1;
        for (int i = 1; i <= n; i++)
        {
            z0 = factor(x, i, p);
            b = (b + z0) % p;
        }
        shifr[1][j] = b;
        z0 = factorial(x, n, p);
        shifr[2][j] = (z0 * aa) % p;
        cout << shifr[0][j] << "\t" << shifr[1][j] << "\t" << shifr[2][j] << endl;
    }
    for (int j = 0; j < len; j++)
    {
        a = shifr[1][j] - shifr[0][j];
        z0 = f3(shifr[2][j], p);
        b = (z0 * a * aa) % p;
        if (b < 0) b += p;
        cout << b << "\t" << char(b) << endl;
    }
    return 0;
}

int factor(int x, int i, int p)
{
    int z = 1;
    for (int k = 1; k <= i; k++)
        z = (z * x) % p;
    int z1 = 1;
    for (int k = 1; k <= i; k++)
        z1 = (z1 * k) % p;
    int z0 = f3(z1, p);
    z0 = (z0 * z) % p;
    return z0;
}

int factorial(int x, int i, int p)
{
    int z = 1;
    for (int k = 1; k <= i - 1; k++)
        z = (z * x) % p;
    int z1 = 1;
    for (int k = 1; k <= i; k++)
        z1 = (z1 * k) % p;
    int z0 = f3(z1, p);
    z0 = (z0 * z) % p;
    return z0;
}

int f3(int t, int p)
{
    int z0 = 0;
    for (int i = 1; i <= p - 1; i++)
        if ((i * t) % p == 1) z0 = i;
    return z0;
}