problem 55

problem51to60/problem53.py

@@ -1,4 +1,6 @@
 # problem 53 
+# straight forward solution is very fast
+#  time complexity: O(n^2 * n) = O(n^3)   
 def combin(n,r):
 	return frac(n) / ( frac(n-r) * frac(r))
 

problem51to60/problem55.py

@@ -0,0 +1,21 @@
+# problem 55
+def is_palindrome(n):
+	orig_n = n
+	n_str = str(n)
+	n_rev = int(n_str[::-1])
+	for i in range(50):
+		sum = n_rev + n
+		if str(sum) == str(sum)[::-1]:
+			print str(orig_n)+ " is palindromic!"
+			return True
+		n = sum
+		n_rev = int(str(n)[::-1])
+	return False
+
+count = 0
+for i in range(1,10000):
+	if not is_palindrome(i):
+		count += 1
+
+print count
+