Change prime_sieve_eratosthenes.py to return list (#8062)

Author: tianyizheng02

maths/prime_sieve_eratosthenes.py

@@ -1,45 +1,54 @@
 """
 Sieve of Eratosthenes
 
-Input : n =10
+Input: n = 10
 Output: 2 3 5 7
 
-Input : n = 20
+Input: n = 20
 Output: 2 3 5 7 11 13 17 19
 
 you can read in detail about this at
 https://en.wikipedia.org/wiki/Sieve_of_Eratosthenes
 """
 
 
-def prime_sieve_eratosthenes(num):
+def prime_sieve_eratosthenes(num: int) -> list[int]:
     """
-    print the prime numbers up to n
+    Print the prime numbers up to n
 
     >>> prime_sieve_eratosthenes(10)
-    2,3,5,7,
+    [2, 3, 5, 7]
     >>> prime_sieve_eratosthenes(20)
-    2,3,5,7,11,13,17,19,
+    [2, 3, 5, 7, 11, 13, 17, 19]
+    >>> prime_sieve_eratosthenes(2)
+    [2]
+    >>> prime_sieve_eratosthenes(1)
+    []
+    >>> prime_sieve_eratosthenes(-1)
+    Traceback (most recent call last):
+    ...
+    ValueError: Input must be a positive integer
     """
 
-    primes = [True for i in range(num + 1)]
-    p = 2
+    if num <= 0:
+        raise ValueError("Input must be a positive integer")
+
+    primes = [True] * (num + 1)
 
+    p = 2
     while p * p <= num:
         if primes[p]:
             for i in range(p * p, num + 1, p):
                 primes[i] = False
         p += 1
 
-    for prime in range(2, num + 1):
-        if primes[prime]:
-            print(prime, end=",")
+    return [prime for prime in range(2, num + 1) if primes[prime]]
 
 
 if __name__ == "__main__":
     import doctest
 
     doctest.testmod()
-    num = int(input())
 
-    prime_sieve_eratosthenes(num)
+    user_num = int(input("Enter a positive integer: ").strip())
+    print(prime_sieve_eratosthenes(user_num))