human
Please write the algorithm for the sieve of Eratosthenes in Python code.
gpt
Here is a Python implementation of the Sieve of Eratosthenes algorithm:

def sieve_of_eratosthenes(n):
    # create a list of all numbers from 2 to n
    numbers = [x for x in range(2, n+1)]

    # loop up to the square root of n
    for i in range(2, int(n**0.5)+1):
        # if i is in the list, then remove all its multiples from the list
        if i in numbers:
            for j in range(i**2, n+1, i):
                if j in numbers:
                    numbers.remove(j)

    # all remaining numbers in the list are prime
    return numbers
human
Please write the alogorithm for Caesar Cipher's way of encrypting in Python code.
gpt
Here is a Python implementation of the Caesar Cipher encryption algorithm:

``` python
def caesar_cipher_encrypt(plain_text, shift):
    """
    Encrypts the given plaintext using the Caesar Cipher algorithm with the given shift value.
    
    :param plain_text: the plaintext to be encrypted
    :param shift: the shift value used for encryption
    :return: the encrypted ciphertext
    """
    cipher_text = ""
    for char in plain_text:
        if char.isalpha():
            # Get the ASCII value of the character
            ascii_val = ord(char)
            
            # Determine whether the character is uppercase or lowercase
            if char.isupper():
                # Shift the ASCII value by the specified number of positions and wrap around if necessary
                shifted_ascii_val = ((ascii_val - 65 + shift) % 26) + 65
                
            else:
                shifted_ascii_val = ((ascii_val - 97 + shift) % 26) + 97
                
            # Convert the shifted ASCII value back to a character and add it to the ciphertext
            cipher_text += chr(shifted_ascii_val)
        else:
            # Add non-alphabetic characters to the ciphertext unchanged
            cipher_text += char
            
    return cipher_text
```

This function takes in two parameters: the plaintext to be encrypted, and the shift value used for encryption. The function then loops over each character in the plaintext, checking whether it is an alphabetic character. If it is, the function determines whether it is uppercase or lowercase, shifts the ASCII value of the character by the specified number of positions, wraps around if necessary, and converts the shifted ASCII value back to a character. If the character is not alphabetic, it is added to the ciphertext unchanged. The encrypted ciphertext is then returned.