On Mon, Apr 5, 2010 at 12:17 PM, Ian Gorse <[email protected]> wrote: > Over at the Project Euler forum a ivan_adrian_k posted a fairly simple > question > > "Find the only 4-digit integer which the product of its digits is > equal to the first two digits of the number, and the sum of its digits > is equal to the last two digits of the number" > > He then goes on to say.. > "If you can answer it correctly, can you find all the 5-digit integers > which has similar property, the product of its digits is equal to the > first three digits of the number, and the sum of its digits is equal > to the last two digits of the number?"
Here is how I might tackle that one: digits=: 10#.inv] sum=:+/"1...@digits prd=:*/"1...@digits sel=: #~ ] = sum + 100 * prd sel 1e3}.i.1e4 NB. four digit numbers sel 1e4}.i.1e5 NB. five digit numbers -- Raul ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
