From 317cf09e71221da7217bbe302bdf10c8bfc191b1 Mon Sep 17 00:00:00 2001
From: Julien Lengrand-Lambert <julien@lengrand.fr>
Date: Mon, 16 Jan 2012 10:47:26 +0100
Subject: [PATCH] Solves problem 14. Prepares problem 12

---
 e_12_notyet.py => e_12.py |  0
 e_14.py                   | 36 +++++++++++++++++++++++++++++++++++-
 2 files changed, 35 insertions(+), 1 deletion(-)
 rename e_12_notyet.py => e_12.py (100%)

diff --git a/e_12_notyet.py b/e_12.py
similarity index 100%
rename from e_12_notyet.py
rename to e_12.py
diff --git a/e_14.py b/e_14.py
index 35a673d..e60f0af 100755
--- a/e_14.py
+++ b/e_14.py
@@ -27,8 +27,42 @@ def longest_chain(max_value):
     Returns the starting number under max_value that produces the longest 
     chain given the sequence.
     """
+    max_len = 1
+    seed = 1
+    for val in range(1, max_value + 1):
+        curr_len = seq_len(val)
+        if curr_len > max_len:
+            max_len = curr_len
+            seed = val
+
+    return seed
+
+def seq_len(value):
+    """
+    Returns the sequence length for a given value
+    """
+    val = value
+    seq = [val]
     
-    return 1
+    while val != 1:
+        val = sequence(val)
+        seq.append(val)
+    return len(seq)
+
+def is_even(value):
+    """
+    Returns true if the given value is even, false otherwise
+    """
+    return (value % 2 == 0)
+
+def sequence(value):
+    """
+    Returns value / 2 if value is even, 3 * n + 1 otherwise.
+    """
+    if is_even(value):
+        return value / 2
+    else:
+        return 3 * value + 1        
 
 if __name__ == '__main__':
     print "Answer : %d" % (longest_chain(1000000))