Validate an IP address (IPv4). A valid IPv4 address must be in the form of XXX.XXX.XXX.XXX, where XXX is a number from 0-255.
Run length encoding (RLE) is a very simple form of lossless data compression which runs on sequences having same value occurring many consecutive times and it encode the sequence to store only a single value and its count.
Given a line of text, reverse the text without reversing the individual words.
Given a string and a integer k, print the string in zig-zag form in k rows.
Find the length of longest contiguous substring of a string, such that the length of the substring is 2*N digits and the sum of the leftmost N digits is equal to the sum of the rightmost N digits. If there is no such substring, return 0.
Given a string, inplace remove all occurrences of “AB” and “C” from it.
Given a text, find all occurrences of a given pattern in it.
Given a list of words, efficiently group all anagrams together. X and Y are anagrams if by rearranging the letters of X, we can get Y using all the original letters of X exactly once.
Given a string, find first K non-repeating characters in it by doing only single traversal of it. For example, if the string is ABCDBAGHCHFAC and K = 3, output would be D G F
Given a list of words and a pattern, find all words in the list that follows same order of characters as that of given pattern.
Given N lists of characters and a number whose digits lies between [1-N], print all possible combinations by replacing its digits with characters of the corresponding list. If any digit of the number gets repeated, it should be replaced by same character considered in its previous occurrence.
Given a sequence of numbers between [2-9], print all possible combinations of words formed from mobile keypad have some digits associated with each key.
Given a string, find all possible palindromic substrings in it.
Given two strings, determine if they are isomorphic. Two strings X and Y are called isomorphic if all occurrences of each character in X can be replaced with another character to get Y and vice-versa.