Add comments

Added comments to the C code for all the problems solved so far.

Python/p041.py

@@ -15,14 +15,18 @@ def count_digits(n):
 def main():
     start = default_timer()
 
-    for i in range(7654321, 0, -2):
-        if is_pandigital(i, count_digits(i)) and is_prime(i):
-            print('Project Euler, Problem 41')
-            print('Answer: {}'.format(i))
-            break
+    i = 7654321
 
+    while(i > 0):
+        if is_pandigital(i, count_digits(i)) and is_prime(i):
+            break
+        i = i - 2
+    
     end = default_timer()
 
+    print('Project Euler, Problem 41')
+    print('Answer: {}'.format(i))
+    
     print('Elapsed time: {:.9f} seconds'.format(end - start))
 
 if __name__ == '__main__':