## Infix to Postfix

What is an infix expression? Expression in the form of ‘operand’ ‘operator’ ‘operand’ is called infix expression. Example:  a+b What is postfix expression? Expression in the form of ‘operand’ ‘operand’ ‘operator’ is called postfix expression. Example:  ab+ What is the need of infix to postfix conversion? Infix expression is easy …

## Topological Sorting

Given a directed acyclic graph, topologically sort the graph nodes. Topological Sorting Example Topological sorting of above graph is -> {1,2,3,0,5,4} Theory Topological Sorting is done for a Directed Acyclic Graph (DAG). A DAG has no cycles in it. ie, there is no such path starting from any node of …

## Quick Sort

Quick Sort is a sorting algorithm. Given an unsorted array sort it using quick sort algorithm. Example Input: {8, 9, 5, 2, 3, 1, 4} Output: {1, 2, 3, 4, 5, 8, 9} Theory It’s a Divide and Conquer sorting Algorithm. It picks a pivot element in the array, splits …

## Reverse a linked list

Problem Statement The problem “reverse a linked list” states that we are given the head of the linked list. We have to reverse the linked list by changing the links between them and return the head of the reversed linked list. Example 10->20->30->40->NULL NULL<-10<-20<-30<-40 Explanation We have reversed the linked …

## Heap Sort

Heap sort is a comparison based sorting technique that is based on a Binary Heap data structure. HeapSort is similar to a selection sort where we find the maximum element and then place that element at the end. We repeat this same process for the remaining elements. Given an unsorted …

## Dijkstra Algorithm

Dijkstra is the shortest path algorithm. Dijkstra algorithm is used to find the shortest distance of all nodes from the given start node. It logically creates the shortest path tree from a single source node, by keep adding the nodes greedily such that at every point each node in the …

## Implement Two Stacks in an Array

Problem Statement In the “Implement Two Stacks in an Array” problem we have to implement two stacks in an array such that, if the user wants to push an element in either of two stacks then there should not be an error till the array gets full. Example Push 5 …

## Count of Triplets With Sum Less than Given Value

Problem Statement We have given an array containing N number of elements. In the given array, Count the number of triplets with a sum less than the given value. Example Input a[] = {1, 2, 3, 4, 5, 6, 7, 8} Sum = 10 Output 7 Possible triplets are : …

## Next Greater Element in an Array

Problem Statement Given an array, we will find the next greater element of each element in the array. If there is no next greater element for that element then we will print -1, else we will print that element. Note: Next greater element is the element that is greater and …

## Find Triplet in Array With a Given Sum

Problem Statement Given an array of integers, find the combination of three elements in the array whose sum is equal to a given value X. Here we will print the first combination that we get. If there is no such combination then print -1. Example Input N=5, X=15 arr[] = …

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