Algorithms Number of substrings in a string divisible by 6 Given a string of integers, find the count of sub-strings of given string which are divisible by 6. This problem can be solved using Dynamic Programming in O(N) time complexity where N is the length of the string.

Algorithms Minimum number of increment operations to make K elements of an array equal Given an array arr[] of n elements and an integer k, the task is to make any k elements of the array equal by performing only increment operations. This is solved using sliding window technique.

Data Structures Dynamic Stack Dynamic Stack, just like Dynamic Array, is a stack data structure whose the length or capacity (maximum number of elements that can be stored) increases or decreases in real time based on the operations (like insertion or deletion) performed on it.