1 files changed, 76 insertions, 0 deletions
diff --git a/challenge-168/roger-bell-west/python/ch-2.py b/challenge-168/roger-bell-west/python/ch-2.py
new file mode 100755
index 0000000000..3811fded6f
--- /dev/null
+++ b/challenge-168/roger-bell-west/python/ch-2.py
@@ -0,0 +1,76 @@
+#! /usr/bin/python3
+
+import unittest
+
+from math import sqrt,floor,gcd
+from collections import deque
+
+def genprimes(mx):
+  primesh=set(range(2,4))
+  for i in range(6,mx+2,6):
+    for j in range(i-1,i+2,2):
+      if j <= mx:
+        primesh.add(j)
+  q=deque([2,3,5,7])
+  p=q.popleft()
+  mr=floor(sqrt(mx))
+  while p <= mr:
+    if p in primesh:
+      for i in range(p*p,mx+1,p):
+        primesh.discard(i)
+    if len(q) < 2:
+      q.append(q[-1]+4)
+      q.append(q[-1]+2)
+    p=q.popleft()
+  primes=list(primesh)
+  primes.sort()
+  return primes
+
+def primefactor(n):
+  f=dict()
+  m=n
+  for p in genprimes(floor(sqrt(n))):
+    while (m % p == 0):
+      m //= p
+      if p in f:
+        f[p] += 1
+      else:
+        f[p] = 1
+    if m==1:
+      break
+  if m > 1:
+    if m in f:
+      f[m] += 1
+    else:
+      f[m] = 1
+  return f
+
+def homeprime(n0):
+  n = n0
+  while True:
+    t = primefactor(n)
+    tk = list(t.keys())
+    tk.sort()
+    if len(tk) == 1 and t[tk[0]] == 1:
+      break
+    ns = ""
+    for d in tk:
+      ds = str(d)
+      for i in range(t[d]):
+        ns += ds
+    n = int(ns)
+  return n
+
+class TestHomeprime(unittest.TestCase):
+
+        def test_ex1(self):
+          self.assertEqual(homeprime(10),
+                           773,
+                           'example 1')
+
+        def test_ex2(self):
+          self.assertEqual(homeprime(16),
+                           31636373,
+                           'example 2')
+
+unittest.main()