String Algorithms

Persistent Trie

In this article, we discuss the Trie data structure and how to make it persistent to solve various problems optimally.

Longest Substring with at Least K repeating characters

In this article, we have presented two algorithms to find the Longest Substring with at Least K repeating characters.

Maximum String Partition problem: Partition Labels

In this article, we have explored approaches to solve the maximum string partition problem (Partition Labels) efficiently.

Algorithms

Substring with Concatenation of All Words

In this article, we have explained two approaches to solve the problem Substring with Concatenation of All Words. This involves the idea of Hash Map and Two Pointer.

Algorithms

ZigZag Conversion of String with N rows

In this article, we have solved the problem of ZigZag Conversion of String with N rows. We take a string and a number N (rows) as input and distribute the string in ZigZag fashion among N rows and print the final string.

Algorithms

Longest Common Prefix

In this article, we are going to explore different approaches to find the longest common prefix between two strings. Same techniques can be applied to find the Longest Common Prefix for multiple strings.

Algorithms

Longest substring without repeating characters

In this article, we have explained three approaches to the problem of finding Longest substring without repeating characters. This involves the use of Hash Map with the clever use of start and end index.

Algorithms

Longest Common Suffix Problem

In this article, we will see how we can find the longest common suffix (i.e ending) that all the strings given to us have. We shall start with the brute-force approach for two strings. Following this, we will implement the Trie data structure to solve the problem for more than two strings.

Algorithms

Deleting Duplicate Characters of String

We have explored the problem of Deleting Duplicate Characters of String such that the resulting string is lexicographically the smallest among all possibilities.

Algorithms

Number of sub-strings with each character occurring even times

This article discusses different algorithmic approach which we can use to find number of sub-strings with each character in it occurring even number times for a given string.

Algorithms

Number of distinct substrings of length K

We have explained the approach to find the Number of distinct substrings of length K using Rolling hash technique, hash table and brute force approach.

Algorithms

Generate all sub-strings of a string

We have explored the approach of generating / printing all sub-strings of a given String and have provided the implementation to do so. The time complexity to generate all substring is O(N^3) time and there are O(N^2) sub-strings for a string of length N.

Algorithms

Number of Substrings with distinct characters

We have explored various algorithms that will help us in determining the number of substrings that a string can have with distinct characters.

String Algorithms

Number of palindromic substrings in a string

A string is a palindrome when it reads the same backward as forward and a substring is a contiguous sequence of characters within the string. We have discussed multiple approaches to find the number of palindromic substrings in a given string.

Algorithms

Check if a string is a subsequence of another string

In this problem, we will see how we can check whether a string is a subsequence of another string. We have solved this in O(N) time using an efficient approach.

Algorithms

Number of substrings with exactly k distinct characters

In this problem, we are given a string and our job is to count the total number of substrings of the given string that contains exactly k distinct characters. We have explored 3 approaches to solve this.

Algorithms

Shift OR algorithm for String Matching

Shift OR algorithm uses bitwise techniques to check whether the given pattern is present in the string or not. It is efficient if the pattern length is lesser than the memory-word size of the machine

Algorithms

Convert one string to another by changing all occurrence of a character to another

We will be solving Check if one string can be converted to another by changing all occurrence of a character to another character problem using the Union and Find algorithm.

String Algorithms

Minimum number of operations to convert binary string to self-destructing

We will explore algorithms to find the Minimum number of operations to convert a binary string to a self-destructing string.

Algorithms

Longest common substring using rolling hash approach

We can solve the longest common substring problem using the rolling hash technique in O(N * log(N)^2) time and O(N) space which is significantly better than other approaches.

Algorithms

Find number of substrings with same first and last characters

You are given a string lets say "S" , you need to find the number of all contiguous substrings (part of "S") starting and ending with the same character.

Algorithms

Word Break Problem

In this article we are going to talk about a very interesting problem: Word Break Problem. This can be solved using Dynamic Programming [O(N^2) time, O(N^2) space].

Software Engineering

Reverse a String (word by word) in C

In this problem, we have reversed a string or text word by word in C. The strategy to do this is important and tests C implementation skill.

Algorithms

Number of times characters of a string is present in another string

In this article, we have explored the algorithm to find the Number of times characters of a string is present in another string. This can be solved in O(N^2) time.

Algorithms

First Unique Character in a String

In this article, we need to find first unique i.e non-repeating character in a given string and return the index or else if no such character exists we return -1.