+ SphereCollatz.py. Resolves #5

SphereCollatz.py

@@ -0,0 +1,100 @@
+#!/usr/bin/env python3
+
+# ------------------------------
+# Copyright (C) 2014
+# Mark Sandan
+# ------------------------------
+# -------
+# imports
+# -------
+
+import sys
+# ----
+# main
+# ----
+
+collatz_solve(sys.stdin, sys.stdout)
+
+# ------------
+# collatz_read
+# ------------
+
+def collatz_read (r) :
+    """
+    read two ints
+    r is a reader
+    return a list of the two ints, otherwise a list of zeros
+    """
+    s = r.readline()
+    if s == "" :
+        return []
+    a = s.split()
+    return [int(v) for v in a]
+
+# ------------
+# collatz_eval
+# ------------
+
+def collatz_eval (i, j) :
+    """
+    i is the beginning of the range, inclusive
+    j is the end       of the range, inclusive
+    return the max cycle length in the range [i, j]
+    """
+    # <your code>
+    c_len=0
+    end=j+1
+    result=0
+    for num in range(i,end):
+        result=cycle_length(num)
+        if c_len < result:
+            c_len=result
+
+    return c_len
+
+# -------------
+# cycle_length
+# -------------
+def cycle_length (n) :
+    assert n > 0
+    c = 1
+    while n > 1 :
+        if (n % 2) == 0 :
+            n = (n // 2)
+        else :
+            n = (3 * n) + 1
+        c += 1
+    assert c > 0
+    return c
+
+# -------------
+# collatz_print
+# -------------
+
+def collatz_print (w, i, j, v) :
+    """
+    print three ints
+    w is a writer
+    i is the beginning of the range, inclusive
+    j is the end       of the range, inclusive
+    v is the max cycle length
+    """
+    w.write(str(i) + " " + str(j) + " " + str(v) + "\n")
+
+# -------------
+# collatz_solve
+# -------------
+
+def collatz_solve (r, w) :
+    """
+    read, eval, print loop
+    r is a reader
+    w is a writer
+    """
+    while True :
+        a = collatz_read(r)
+        if not a :
+            return
+        i, j = a
+        v = collatz_eval(i, j)
+        collatz_print(w, i, j, v)