I occasionally try to solve Quora math problems to polish my J skills. Here's a problem that
* "The integer 2018 can be written uniquely as the sum of consecutive squared integers. How many squares does the sum contain?"* a=.2^~i.100 NB. Find how many consecutive squared integers it takes to sum to 2018. Try each length until I get a hit. +/2018=+/"1]5,\a 0 +/2018=+/"1]6,\a 0 +/2018=+/"1]7,\a 0 +/2018=+/"1]8,\a 0 +/2018=+/"1]9,\a 0 +/2018=+/"1]10,\a 0 +/2018=+/"1]11,\a 0 +/2018=+/"1]12,\a 1 NB. A hit! +/2018=+/"1]13,\a 0 So the answer is 12 List them: b#~2018=+/"1 b=.12,\a 49 64 81 100 121 144 169 196 225 256 289 324 Is there a way to do this search without explicit looping? Skip Skip Cave Cave Consulting LLC ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
