ReplacementCipher

#include <iostream>
#include <string>
#include <algorithm>
#include <cstdint>

using namespace std;

static string alphabet = " ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"s;

static string ReplacementCipherENcode(const string& Slogan, const string& Alphabet,
    const string StrForENcoding)
{
    string encoding_alphabet(Alphabet);
    for_each(Slogan.begin(), Slogan.end(), [&encoding_alphabet](const auto& symbol) {
        remove(encoding_alphabet.begin(), encoding_alphabet.end(), symbol);
    });
    rotate(encoding_alphabet.rbegin(), encoding_alphabet.rbegin() + Slogan.length(),
                                                            encoding_alphabet.rend());
    encoding_alphabet.replace(0, Slogan.length(), Slogan);

    string ENcoded_str;
    for(const auto& symbol: StrForENcoding)
    {
        ENcoded_str.push_back(encoding_alphabet[Alphabet.find(symbol)]);
    }
    return ENcoded_str;
}

static string ReplacementCipherDEcode(const string& Slogan, const string& Alphabet,
    const string StrForDEcoding)
{
    string encoding_alphabet(Alphabet);
    for_each(Slogan.begin(), Slogan.end(), [&encoding_alphabet](const auto& symbol) {
        remove(encoding_alphabet.begin(), encoding_alphabet.end(), symbol);
    });
    rotate(encoding_alphabet.rbegin(), encoding_alphabet.rbegin() + Slogan.length(),
                                                            encoding_alphabet.rend());
    encoding_alphabet.replace(0, Slogan.length(), Slogan);

    string DEcoded_str;
    for(const auto& symbol: StrForDEcoding)
    {
        DEcoded_str.push_back(Alphabet[encoding_alphabet.find(symbol)]);
    }
    return DEcoded_str;
}

int main()
{
    static string str_for_encoding = "CRYPTOGRaPHY EXAMpLE TEmPlATe"s;
    cout << "Строка для кодирования: " << str_for_encoding << endl;

    static string slogan = "CRYPTO"s;
    cout << "Ключ\\слоган " << slogan << endl;

    const string ENCodedStrR(ReplacementCipherENcode(slogan, alphabet,
        str_for_encoding));
    cout << "Зашифрованная строка: " << ENCodedStrR << endl;
    cout << "Дешифрованная строка: " << ReplacementCipherDEcode(slogan, alphabet,
        ENCodedStrR) << endl;
}