I am pretty pleased that I completed Project Euler Q4. Question:
A palindromic number reads the same both ways. The largest palindrome made from the product of two 2-digit numbers is 9009 = 91 99. Find the largest palindrome made from the product of two 3-digit numbers. https://projecteuler.net/problem=4 My solution: base =. "."0 ": NB. Tests if y value is palindrome. is_palindrome =. (# =)@:(=|.)@:base NB. multiply all 3 digit nums (100 ~ 999) mult =: (* is_palindrome"0) @ (*/) NB. Create list of 3 digit nums. list =. 100+ i.900 (>./)@:, list mult list Although I'm glad got the answer, I'm wondering if it could be made terser, or if there is a much terser way to solve it? I went for a brute force approach. For comparison here is a Haskell answer I found: maximum[a*b|a<-[100..999],b<-[a..999],reverse(show(a*b))==show(a*b)] Regards. ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
