Given a number, check if it is power of four or not.
Given M sorted lists of variable length, print them in sorted order efficiently.
Given a string, calculate its rank among all its lexicographically sorted permutations. For example, consider below lexicographically sorted permutations
Given a linked list containing 0’s, 1’s and 2’s, sort linked list by doing single traversal of it.
Given two Boolean arrays X and Y, find the length of longest continuous sequence that starts and ends at same index in both arrays and have same sum. In other words, find max(j-i+1) for every j >= i where sum of sub-array X[i, j] is equal to sum of sub-array Y[i, j].
Implement Quicksort efficiently for inputs containing many repeated elements. Quicksort exhibits poor performance for inputs that contain many repeated elements. The problem is clearly visible when all the input elements are equal. Then at each recursion, the left partition is empty (no input values are less than the pivot), and the right partition …
In this article, we will implement Ternary Search algorithm and compare its performance with Binary Search.
Given an integer, reverse its bits using binary operators. The idea is to initialize the result by 0 (all bits 0) and process the given number starting from its least significant bit. If the current bit is 1, then we set the corresponding most significant bit in the result and finally move on …
Given a mobile keypad having digits from [0-9] associated with each key, count total possible combinations of digits having length n. We can start with any digit and press only four adjacent keys of any digit. Keypad also contains * and # key which we are not allowed to press.
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.
Huffman Coding is a algorithm for doing data compression and it forms the basic idea behind file compression. This post talks about fixed length and variable length encoding, uniquely decodable codes, prefix rules and construction of Huffman Tree.
Given a directed graph, check if it is strongly connected or not. A directed graphs is said to be strongly connected if every vertex is reachable from every other vertex.
Find all N-digit strictly increasing numbers where N varies from [1 to 9]. If we process the number from left to right and for every pair of adjacent digits, if every digit is greater than the preceding digit, we can say that the digits are strictly increasing.
Given a binary tree, write an efficient algorithm to check if tree is height balanced or not. In a height balanced tree, the absolute difference between height of left subtree and right subtree for every node is 0 or 1.