Category: DP

Longest Common Substring problem

The longest common substring problem is the problem of finding the longest string (or strings) that is a substring (or are substrings) of two strings.

Longest Common Subsequence | Introduction & LCS Length

The longest common subsequence (LCS) problem is the problem of finding the longest subsequence that is present in given two sequences in the same order. i.e. find a longest sequence which can be obtained from the first original sequence by deleting some items, and from the second original sequence by deleting other items.  

Introduction to Dynamic Programming

  Dynamic programming is a method for solving a complex problem by breaking it down into a collection of simpler subproblems, solving each of those subproblems just once, and storing their solutions using a memory-based data structure (array, map,etc). Each of the subproblem solutions is indexed in some way, typically based on the values of …

Calculate sum of all elements in a sub-matrix in constant time

Given a M x N matrix and two coordinates (p, q) and (r, s) which represents top-left and bottom-right coordinates of a sub-matrix of the given matrix, calculate the sum of all elements present in the sub-matrix in O(1) time. Here, 0 < = p < r < M and 0