This category contains all the posts related to Algorithms. For e.g.: Sorting, Hashing, Searching, Tree Traversals, Graph Theory etc.

Pattern Finding – KMP Algorithm

Introduction Now that you are fully equipped with the Boyer Moore Algorithm and have a notion of Pattern Finding. I would suggest you to get deeper into pattern finding. You can read about the benefits of pattern finding in my previous post about Boyer Moore. This post will try to make you familiar with all the thought processes which you can use to exploit the known properties of texts and patterns using KMP Algorithm. However, Boyer Moore seems to be slightly intuitive, this one is a real geeky way of finding patterns. Knuth Morris Pratt Yes! this is what KMP stands for, you can learn ...
Read More

Pattern Finding – Boyer Moore

Introduction String matching problems are important part of many Programming Contests and also find applications in real world problems. Imagine you are asked to implement a text editor. What are few of the most common operations in a text editor? Copy and Paste. Search and Replace. The performance of your text editor will completely depend on how efficiently it can search and/or replace patterns in a huge text. Basics of Pattern Finding In a given pattern matching problem, we have two strings one is called the text T and the other is called the pattern P. The task is to find th...
Read More

Solving Recurrences – Master Method

Introduction This post is to be read in continuation to the Divide and Conquer methodology for e.g. the Merge Sort problem. This post is an extension over the problem of solving recurrences or recurrence equations. There are several ways of solving recurrences namely Substitution Method, Master Method and Recurrence Tree method. The most confusing one or may I say relatively complex one is the Master Theorem. Here we will discuss the same. Master Theorem What does it solve? Not all the recurrences can be solved using the Master Theorem, but it still solves a large family of recurrences....
Read More

Dynamic Programming – Longest Palindromic Sequence

[nextpage title="Introduction"] Palindromes are fascinating character sequences in a string. A palindrome is a string which reads the same when read from either of the ends. This post in particular talks about palindromic sub sequences. To know more about a sub sequence, please check my post on Longest Common Sub sequence. A palindromic sequence means a sequence of characters which is a palindrome. Now, we must understand it clearly that we are talking about a sub sequence and not a substring. Understanding the Longest Palindromic Subsequence problem better It is really easy to say if...
Read More

Interleaving Strings

Problem Statement This is a question from one of the interview experiences. The statement, "Given three strings A, B and C find if C is an interleaving of A and B." Interleaving is defined as below: A string C is said to be an interleaving of two strings A and B if C contains a sub sequence of A and B such that the relative order of characters in A and in B are preserved in C. For e.g. : A - ABCD B - BACDX C - ABACDXBCD The Idea - Interleaving Strings Here I am not giving any solution which is less than O(M*N) solution where M is the length of the shortest string among A and B...
Read More