Webseiten-Werkzeuge


Non-unique Elements

You are given a non-empty list of integers (X). For this task, you should return a list consisting of only the non-unique elements in this list. To do so you will need to remove all unique elements (elements which are contained in a given list only once). When solving this task, do not change the order of the list. Example: [1, 2, 3, 1, 3] 1 and 3 non-unique elements and result will be [1, 3, 1, 3].

Examples
Input Output
[1, 2, 3, 1, 3] [1, 3, 1, 3]
[1, 2, 3, 4, 5] []
[5, 5, 5, 5, 5] [5, 5, 5, 5, 5]
[10, 9, 10, 10, 9, 8] [10, 9, 10, 10, 9]
Solution
/ζ(\d+)(.*)ζ\1/ζ$1$2λ$1/
/ζ(\d+)(.*)λ\1/λ$1$2λ$1/
/ζ(\d+)(, )?//
/, ]/]/
/[ζλ]//g !
/(\d+)/ζ$1/g 
Reference