Kata

In this kata, you will sort elements in an array by decreasing frequency of elements. If two elements have the same frequency, sort them by increasing value.

solve([2,3,5,3,7,9,5,3,7]) = [3,3,3,5,5,7,7,2,9]
-- We sort by highest frequency to lowest frequency.
-- If two elements have same frequency, we sort by increasing value.

solve({2,3,5,3,7,9,5,3,7}) == {3,3,3,5,5,7,7,2,9}
// We sort by highest frequency to lowest frequency.
// If two elements have same frequency, we sort by increasing value.

Solution.sortByFrequency(new int[]{2, 3, 5, 3, 7, 9, 5, 3, 7});
// Returns {3, 3, 3, 5, 5, 7, 7, 2, 9}
// We sort by highest frequency to lowest frequency.
// If two elements have same frequency, we sort by increasing value.

More examples in test cases.

Good luck!

Please also try Simple time difference