Sort elements by frequency

Print the elements of an array in the decreasing frequency if 2 numbers have same frequency then print the one which came first.

Examples:  

Input:  arr[] = {2, 5, 2, 8, 5, 6, 8, 8}
Output: arr[] = {8, 8, 8, 2, 2, 5, 5, 6}

Input: arr[] = {2, 5, 2, 6, -1, 9999999, 5, 8, 8, 8}
Output: arr[] = {8, 8, 8, 2, 2, 5, 5, 6, -1, 9999999}

Sort elements by frequency _ Set 1: https://www.geeksforgeeks.org/sort-elements-by-frequency/