Add solution for problem 63.

2015-09-05 12:21:18 -05:00 · 2015-09-05 12:21:18 -05:00 · f3f4b456ab
parent 20472682ac
commit f3f4b456ab
1 changed files with 6 additions and 0 deletions
--- a/Problem063.hs
+++ b/Problem063.hs
@ -0,0 +1,6 @@
+-- How many n-digit positive integers exist which are also an nth power?
+import Data.List (nub)
+
+-- If x >= 10 then x^n >= 10^n and thus has more than n digits.
+-- If n >= 22 then 9^n < 10^(n-1) and thus has fewer than n digits.
+main = print $ length $ nub [ x^n | n <- [1..21], x <- [1..9], x^n >= 10^(n-1) ]