Data commit

Task/Primality-by-trial-division/Python/primality-by-trial-division-1.py

@@ -0,0 +1,2 @@
+def prime(a):
+    return not (a < 2 or any(a % x == 0 for x in xrange(2, int(a**0.5) + 1)))

Task/Primality-by-trial-division/Python/primality-by-trial-division-2.py

@@ -0,0 +1,4 @@
+def prime2(a):
+    if a == 2: return True
+    if a < 2 or a % 2 == 0: return False
+    return not any(a % x == 0 for x in xrange(3, int(a**0.5) + 1, 2))

Task/Primality-by-trial-division/Python/primality-by-trial-division-3.py

@@ -0,0 +1,13 @@
+def prime3(a):
+    if a < 2: return False
+    if a == 2 or a == 3: return True # manually test 2 and 3
+    if a % 2 == 0 or a % 3 == 0: return False # exclude multiples of 2 and 3
+
+    maxDivisor = a**0.5
+    d, i = 5, 2
+    while d <= maxDivisor:
+        if a % d == 0: return False
+        d += i
+        i = 6 - i # this modifies 2 into 4 and viceversa
+
+    return True

Task/Primality-by-trial-division/Python/primality-by-trial-division-4.py

@@ -0,0 +1,7 @@
+>>> import re
+>>> def isprime(n):
+    return not re.match(r'^1?$|^(11+?)\1+$', '1' * n)
+
+>>> # A quick test
+>>> [i for i in range(40) if isprime(i)]
+[2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37]