# Category: Stack

## Merging Overlapping Intervals

Given a set of intervals, print all non-overlapping intervals after merging overlapping intervals.

## Decode the given sequence to construct minimum number without repeated digits

Given a sequence consisting of ‘I’ and ‘D’ where ‘I’ denotes increasing sequence and ‘D’ denotes the decreasing sequence. Decode the given sequence to construct minimum number without repeated digits.

## Find ancestors of given node in a Binary Tree

Given a binary tree, find all ancestors of given node in it.

## Inorder Tree Traversal | Iterative & Recursive

Given a binary tree, write iterative and recursive solution to traverse the tree using in-order traversal.   Unlike linked lists, one-dimensional arrays and other linear data structures, which are traversed in linear order, trees may be traversed in multiple ways in depth-first order (in-order, pre-order and post-order) or breadth-first order (level order traversal). Beyond these …

## Preorder Tree Traversal | Iterative & Recursive

Given a binary tree, write iterative and recursive solution to traverse the tree using pre-order traversal.   Unlike linked lists, one-dimensional arrays and other linear data structures, which are traversed in linear order, trees may be traversed in multiple ways in depth-first order (pre-order, pre-order and pre-order) or breadth-first order (level order traversal). Beyond these …

## Postorder Tree Traversal | Iterative & Recursive

Given a binary tree, write iterative and recursive solution to traverse the tree using post-order traversal.   Unlike linked lists, one-dimensional arrays and other linear data structures, which are traversed in linear order, trees may be traversed in multiple ways in depth-first order (post-order, pre-order and post-order) or breadth-first order (level order traversal). Beyond these …

## Check if two binary trees are identical or not | Iterative & Recursive

Write an efficient algorithm to check if two binary trees are identical or not. i.e. if they have identical structure & their contents are also same.     The idea is to traverse both trees and compare value at their root node. If the value matches, we recursively check if left subtree of first tree …

## Reverse text without reversing the individual words

Given a line of text, reverse the text without reversing the individual words.

## Find all binary strings that can be formed from given wildcard pattern

Given a binary pattern that contains ‘?’ wildcard character at few positions, find all possible combinations of binary strings that can be formed by replacing the wildcard character by either 0 or 1.

## Iterative Implementation of Quicksort

Write iterative version of recursive Quicksort algorithm.

## Evaluate given postfix expression

Write code to efficiently evaluate given postfix expression.

## Find duplicate parenthesis in an expression

Given an balanced expression that can contain opening and closing parenthesis, check if the expression contains any duplicate parenthesis or not.

## Check if given expression is balanced expression or not

Given an expression containing opening and closing braces, check if it is balanced or not.

## Best online courses for Data Structures And Algorithms

Friends, this article lists some the of best courses available online on Data Structures and Algorithms. We recommend to go through them to have strong basics.   Data Structures and Algorithms by Dr. Naveen Garg Lecture Series on Data Structures and Algorithms by Dr. Naveen Garg, Department of Computer Science and Engineering, IIT Delhi. Playlist details …