add exercise 4

flyhigher139 · flyhigher139 · commit 0ec241953d30 · 2015-10-06T15:01:57.000+08:00
diff --git a/exercises_4.py b/exercises_4.py
@@ -0,0 +1,49 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+'''
+Create a program that asks the user for a number and then prints out a list of all the divisors of that number. 
+
+(If you don&rsquo;t know what a divisor is, it is a number that divides evenly into another number. 
+    For example, 13 is a divisor of 26 because 26 / 13 has no remainder.)
+'''
+
+n = raw_input('Please input a number: ')
+n = int(n)
+
+# The simplest solution
+res = []
+for i in xrange(2, n):
+    if n % i == 0:
+        res.append(i)
+
+res.append(1)
+res.append(n)
+
+res.sort()
+
+print 'The following are divisors of your input number: '
+print res
+
+# A more efficient solution
+
+from math import sqrt
+
+x = int(sqrt(n))
+
+res2 = []
+for i in xrange(2, x):
+    if n % i == 0:
+        res2.append(i)
+        res2.append(n/i)
+        
+if n == x * x:
+    res.append(x)
+
+res2.append(1)
+res2.append(n)
+
+res2.sort()
+
+print 'The following are divisors of your input number calculated by another way: '
+print res2
