1. Write a program to print all the LEADERS in the array. An element is leader if it is greater than all the elements to its right side. And the rightmost element is always a leader. For example int the array {16, 17, 4, 3, 5, 2}, leaders are 17, 5 and 2.
2. Finding sum of digits of a number until sum becomes single digit
3. Counting frequencies of array elements
4. Write a function that generates a random string of any length
5. find missing number
