# Exercise: Sort by Occurrences

Practice with a real interview exercise.

## We'll cover the following

## Write an `OrderByOccurrences`

method

For this exercise, let’s stop talking about movies. We’ve covered everything we need to solve this exercise so far in this chapter.

Author’s Note: This is an interview question I got when applying for my last position as a software engineer.

Write an `OrderByOccurrences`

method to sort a collection of numbers by the frequency of occurrences of its elements.

For example, the list `[3,2,2,3,3,1]`

after sorted by occurrences would be `[1,2,2,3,3,3]`

since 1 appears once; 2, twice; and 3, three times. If two numbers have the same frequency, they should be in ascending order.

To complete this exercise, fill in the body of the `OrderByOccurrences`

method.

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