Merge pull request #6394 from waltman/branch-for-challenge-172

Branch for challenge 172

1 files changed, 15 insertions, 0 deletions

diff --git a/challenge-172/walt-mankowski/python/primes.py b/challenge-172/walt-mankowski/python/primes.py
new file mode 100644
index 0000000000..5de8c87a61
--- /dev/null
+++ b/challenge-172/walt-mankowski/python/primes.py
@@ -0,0 +1,15 @@
+from math import sqrt
+
+# find the primes up to n using the sieve of Eratosthenes and return
+# them as a list
+def primes_to(n):
+    is_prime = [True] * (n+1)
+    is_prime[0] = is_prime[1] = False
+    for i in range(2, int(sqrt(n))+1):
+        if is_prime[i]:
+            for j in range(i+i, n+1, i):
+                is_prime[j] = False
+
+    return [i for i,val in enumerate(is_prime) if val]
+
+