Szyfr płotkowy

Opis problemu

Szyfrowanie

Implementacja

#include <iostream>

using namespace std;

string encode(string message, int key) {
    string encoded = "";
    int jump, i;

    for (int k = 0; k < key; k++) {
        if (k == key - 1) {
            jump = (key - 1) * 2;
        } else {
            jump = (key - (k + 1)) * 2;
        }

        i = k;

        while (i < message.length()) {
            encoded += message[i];
            i += jump;
        }
    }

    return encoded;
}

int main() {
    string message = "computer science";

    string encoded = encode(message, 3);

    cout << encoded << endl;

    return 0;
}

Deszyfrowanie

Implementacja

#include <iostream>

using namespace std;

string decode(string message, int key) {
    string decoded = message;
    int j = 0;
    int jump, i;

    for (int k = 0; k < key; k++) {
        if (k == key - 1) {
            jump = (key - 1) * 2;
        } else {
            jump = (key - (k + 1)) * 2;
        }

        i = k;

        while (i < message.length()) {
            decoded[i] = message[j];
            j += 1;
            i += jump;
        }
    }

    return decoded;
}

int main() {
    string message = "cu eoptrsinemecc";

    string decoded = decode(message, 3);

    cout << decoded << endl;

    return 0;
}