J examples

The J programming language, developed in the early 1990s by Kenneth E. Iverson and Roger Hui, is an array programming language based primarily on APL.

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Advent of Code 2020

Day 01: Report Repair

… you to find the two entries that sum to 2020 and then multiply those two numbers together.

d=: (".;._2)1!:1<}:}.'_'

*/2{.d/:(2020-d)i.d

… what is the product of the three entries that sum to 2020?

*/ {:"1 (#"1~ 2020&=@:(+/)) |: d {~ ((#: i.@(*/)) 3 ## d)