Find Doubles

Problem Overview

• Identify all integers in a list for which exactly one element in the same list is twice their value.
• Input: list of N integers (0–1000, up to 100,000 items, values may repeat); Output: print qualifying numbers in sorted order to STDOUT.
• Domain: list/data analysis and validation where x and 2x relationships matter.
• From Purestorage interviews; a common coding interview problem and interview question.