## Find all N-digit numbers with given sum of digits

Find all N-digit numbers with equal sum. N varies from [1 to 9] and sum < = 81 (Maximum possible sum in a 9-digit number)

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Find all N-digit numbers with equal sum. N varies from [1 to 9] and sum < = 81 (Maximum possible sum in a 9-digit number)

Convert a given binary tree to BST (Binary Search Tree) by keeping original structure of the binary tree intact.

Implement Quicksort algorithm usingĀ Hoare’s Partitioning scheme.

Given a normal binary tree, convert it to Left-child right-sibling (LC-RS) binary tree.

Given an unsorted array of integers, find a triplet with given sum in it.

Implement Quicksort efficiently for inputs containing many repeated elements.

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.

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.

Given a positive number N, find all combinations of 2*N elements such that every element from 1 to N appears exactly twice and distance between its two appearances is exactly equal to value of the element.

Given a string and a pattern containing wildcard characters i.e. ‘*’ and ‘?’, where ‘?’ can match to any single character in input string and ‘*’ can match to any number of characters including zero characters, design an efficient algorithm to find if the pattern matches with the complete input string or not.

Given an array of integers, find the maximum sum of subsequence of given array where subsequence contains no adjacent elements.

Given an array of integers, find all distinct combinations of given length where repetition of elements is allowed.