How to arrange an array in decreasing order of frequency of each number?

Question

Input : {5, 13, 6, 5, 13, 7, 8, 6, 5}

Output : {5, 5, 5, 13, 13, 6, 6, 7, 8}

The question is to arrange the numbers in the array in

Answer 1

You can probably do it in one pass with a bubble sort type algorithm where you keep a note of the count of the previous value and swap bunches of numbers when you find more of another number.

But - as a first step you should do a 2pass solution, with a std::map/pair to store number or if you are told the range of values in advance use a simple array.