Print Numbers from 1 to N without using loop
Objective: Given a number N, write an program to print from number 1 to N without using loop. Example: N = 20 Output: 1 2 3 4 5 6 7 8 9 10 11 12...
Category: Recursion
Reverse a String using Recursion
Objective: Given a String, write a recursive program to reverse it. Example: Original String: tutorial horizon Reversed String: noziroh lairotut Approach: Take the first character out of the string, add it to the end...
Graph – Find Cycle in Undirected Graph using Disjoint Set (Union-Find)
Objective: Given a graph, check if the graph contains a cycle using disjoint set. Note: Disjoint-set data structure, also called a union–find data structure or merge–find set. Example: Earlier in Detect Cycle in Undirected Graph using DFS we...
Graph – Depth First Search using Recursion
Objective: Given a graph, do the depth first traversal using recursion. Earlier we have seen DFS using stack. In this article we will see how to do DFS using recursion. (Recursion also uses stack...
Print all subarrays of a given array
Objective: Given an array write an algorithm to print all the possible sub arrays. Example: int [] a = {1, 2, 3}; Output: Possible subarrays – {1}, {2}, {3}, {1, 2} , {2, 3}, {1,...
Text Justification Problem (OR Word Wrap Problem)
Objective: Given a list of words and length L. Format the words so that each line will have only L characters and fully justified (left and right justified). Restrictions- You need to fit as many...
Divide and Conquer – Rearrange array elements in special order
Objective: Given an array of integers of size 2n, write an algorithm to arrange them such that first n elements and last n elements are set up in alternative manner. Say n = 3 and...
Find the local minima in a given array
Objective: Given an array of integer write an algorithm to find the local minima. Local Minima: An element is considered as local minima if it is less than both of its neighbors (if neighbors exist)....
Check if array is sorted using recursion
Objective: Given an array of integer write a recursive solution to check if array is sorted. Example: int [] a = {1,2,3,4}; Output: true int [] a = {1,2,3,4,2}; Output: false Approach: This problem can...
Maximum Subarray OR Largest Sum Contiguous Subarray Problem – Divide and Conquer
Objective: The maximum subarray problem is the task of finding the contiguous subarray within a one-dimensional array of numbers which has the largest sum. Example: int [] A = {−2, 1, −3, 4, −1, 2, 1, −5, 4}; Output:...
Maximum difference between two elements where larger element appears after the smaller element
Objective: Given an array A[], write an algorithm to find Maximum difference between two elements where larger element appears after the smaller element or in other words find A[i] and A[j] such that A[j]-A[i]...
Dynamic Programming – Count all paths in 2D Matrix with Obstructions in it
Objective: Given two dimensional matrix, write an algorithm to count all possible paths from top left corner to bottom-right corner. You are allowed to move only in two directions, move right OR move down....
Swap Nodes in pairs in a Linked List by changing links
Objective: Given a linked list write an algorithm to swap nodes in pairs by changing links . Earlier we have seen “Swap Every Kth node in a Linked List“, where we have seen how...
Convert BST to Greater Sum Tree
Objective: Given a binary search tree (BST), convert it into greater sum tree. What is greater sum tree: Greater sum tree is a tree in which every node contains the sum of all the...
Reverse a Linked List in groups of given size ‘K’
Objective: Given a linked list and integer ‘k’, write an algorithm to reverse the linked list in groups of size ‘k’. Example: Approach: Earlier we have seen how to reverse a linked list, solution...