## Find all possible combinations with sum K from a given number N(1 to N) with the repetition of numbers is allowed

Objective: Given two integers N and K, Write an algorithm to find possible combinations that add to K, from the numbers 1 to N.  Condition: An integer from 1 to N can be repeated any number of times in combination. Example: N = 5 K = 3 Output: [1, 1, 1] [1, 2]  N … Read more Find all possible combinations with sum K from a given number N(1 to N) with the repetition of numbers is allowed

## Insert a node in the given sorted linked list.

Objective: Given a linked list in which nodes are sorted in ascending order. Write an algorithm to insert a given node into the linked list so that all the nodes in the list will maintain the sorted order. Example:  Given Linked List:  -> 2, Insert node: 6 New List:  -> 2 -> 6 Given Linked … Read more Insert a node in the given sorted linked list.

## Construct the largest number from the given array.

Objective: Given an array of integers, write an algorithm to construct the largest number possible by appending the array elements.  Example: Given Input: [7, 78] Largest Number Possible: 787 Explanation: two possibilities are 778 and 787. 787 is larger than 778. Given Input: [25, 42, 39] Largest Number Possible: 423925 Approach:  Normal sorting in descending … Read more Construct the largest number from the given array.

## Activity Selection Problem

Objective: The activity selection problem is a combinatorial optimization problem concerning the selection of non-conflicting activities to perform within a given time frame, given a set of activities each marked by a start time (si) and finish time (fi). The problem is to select the maximum number of activities that can be performed by a … Read more Activity Selection Problem

## Find the sum of overlapping elements in two sets

Objective: Given two sets of integers, write an algorithm to print the sum of overlapping elements in two sets. Note: Elements in each set are unique or there are no duplicates within a set. Example: Set 1: [2, 3, 1, 6] Set 2: [4, 0, 6, 7] Sum of overlapping elements: 12 Explanation: Common element … Read more Find the sum of overlapping elements in two sets

## Check the completeness of given binary tree | Set 2 – Using Level Order Traversal

Objective: Given a binary tree, write an algorithm to determine whether the tree is complete or not using Level order traversal. Earlier we had solved this problem by counting the number of nodes in the tree. (Read – Check the completeness of given binary tree | Set 1 – Using Node Count. In this article, … Read more Check the completeness of given binary tree | Set 2 – Using Level Order Traversal

## Check the completeness of given binary tree | Set 1 – Using Node Count

Objective: Given a binary tree, write an algorithm to determine whether the tree is complete or not.  Complete Binary Tree: A binary tree T with n levels is complete if all levels except possibly the last are completely full, and the last level has all its nodes to the left side. Example:  Below is an … Read more Check the completeness of given binary tree | Set 1 – Using Node Count

## Check if the given binary tree is Full or not.

Objective: Given a binary tree, write an algorithm to check if the tree is Full or not. Full binary tree:  A binary tree T is full if each node is either a leaf or possesses exactly two child nodes. See the example below Approach: Do postorder traversal. Check if the node is a leaf node … Read more Check if the given binary tree is Full or not.

## Print Stack in reverse order.

Objective: Given a stack, write a program to print the stack elements in reverse order. Example: Approach: Use Temporary stack: Take temporary stack, and copy all the items from the given stack to a temporary stack. Elements will be stored in a temporary stack in reverse order. Now print elements from the temporary stack and … Read more Print Stack in reverse order.

## Given an array, Print sum of all subsets

Objective: Given an array of numbers, write an algorithm to print all the subsets sum individually.   Example: Given Input: [1, 2] Output: 3 1 2 0 Explanation: subsets are , , , [1, 2] Given Input: [2, 4, 6] 12 6 8 2 10 4 6 0 Approach: Recursion Every element of the array has … Read more Given an array, Print sum of all subsets

## Lexicographically previous permutation With One swap

Objective: Given an array of integers (in particular order or permutation of a set of numbers), write an algorithm to find the lexicographically previous permutation of the given permutation with only one swap.  This problem can also be asked as “Given a permutation of numbers you need to find the next smaller premutation OR largest … Read more Lexicographically previous permutation With One swap

## Find all unique combinations of exact K numbers (from 1 to 9 ) with sum to N

Objective: Given two integers N and K. Write an algorithm to find all the combinations of k numbers which sum to N.  Conditions:  All K numbers must be between 1 and 9 and unique. All numbers in K are positive. Example: N= 5 K=2 Output: [1, 4] [2, 3] N =12 K=3 Output: [1, 2, … Read more Find all unique combinations of exact K numbers (from 1 to 9 ) with sum to N

## Maximum number edges to make Acyclic Undirected/Directed Graph

Given- Given V vertices, what is the maximum number of edges can be added to make Acyclic Undirected Graph. Follow up – what is the maximum number of edges that can be added to make Acyclic Directed Graph. Example:  Approach: For Undirected Graph – It will be a spanning tree (read about spanning tree) where … Read more Maximum number edges to make Acyclic Undirected/Directed Graph

## Evaluation of Prefix Expressions (Polish Notation) | Set 2

Earlier we had discussed how to evaluate prefix expression where operands are of single-digit. In this article, we will discuss how to evaluate prefix expression for any number ( not necessarily single digit.) Prefix notation is a notation for writing arithmetic expressions in which the operands appear after their operators. Let’s assume the below Operands … Read more Evaluation of Prefix Expressions (Polish Notation) | Set 2