A message containing letters from A-Z can be encoded into numbers. To decode an encoded message, all the digits must be grouped then mapped back into letters using the reverse of the mapping

Greedy approach and Dynamic programming both are used for solving optimisation problems. However often we need to use DP since optimal solution cannot be guaranteed by a greedy algorithm.

The number of possible partition of a set of n elements is B(n) known as Bell number. As we know, this problem is NP-Complete i.e. it has non-polynomial time solution.

Quick Sort” is capable of sorting a list of data elements significantly faster (twice or thrice faster) than any of the common sorting algorithms and that’s why it is the favourite topic of interviewers.

Backtracking is a general algorithm for finding solutions to some computational problems, that incrementally builds candidates to the solutions, and abandons a candidate (“backtracks”) as soon as it determines that the candidate cannot possibly be completed to a valid solution.