getDuplicates

You need to figure out a way to find all duplicates in a list of numbers numberList provided to you, and return them in an array sorted in the order they appear in numberList.

Additional constraints for those who really like challenges:

• you’re not allowed to create more variables;
• all operations should be done on the original list;
• the run time should be linear.

Of course, you can choose to ignore these constraints and submit a solution but where is fun in that?

Example

• For numberList = [1,2,1,1,3,2,4,6,5], the output should be
  GetDuplicates(numberList) = [1,2].

Input/Output

• [execution time limit] 0.5 seconds

• [input] array.integer numberList

  List of numbers to check for duplicates.

  Constraints:
  
  0 ≤ numberList.length ≤ 150,
  
  1 ≤ numberList[i] ≤ 4 · 105.

• [output] array.integer

  • Array of duplicates in the order they appear.