Array

Question 1: Arrays: Find numbers with even number of digits

Question 2: Arrays: Find unique numbers that sum upto zero

Question 3: Arrays: Find the k’th smallest/largest element in an array

Question 4: Arrays: Check If N and Its Double Exist

Question 5: Arrays: Move all the negative number in beginning

Question 6: Arrays: Find the union and intersection of two sorted arrays

Question 7: Arrays: Given an array, rotate it one time

Question 8: Arrays: Given an array, find the continuous sub array that has the largest sum, return the sum. 2 solutions in C++

Question 9: Arrays: Minimize the maximum difference between the heights

Question 10: Arrays: Reach the end of the array with minimum jumps. Solution in C++

Question 11: Arrays: Given an array find the duplicate number

Question 12: Arrays: Merge Two Sorted arrays without using extra space

Question 13: Arrays: Kadane Algorithm

Question 14: Arrays: Merge overlapping Intervals solution in C++

Question 15: Arrays: Implement next permutation, which rearranges numbers into the next greater permutation of numbers.

Question 16: Arrays: Inversion Count in an Array

Question 17: Arrays: Optimum Time to Buy and Sell Stock

Question 18: Arrays: Given an unsorted array, and a key. Find 2 elements such that the difference between the elements is equal to the key.

Question 19: Arrays: Find common element in 3 sorted arrays.

Question 20: Arrays: Rearrange the array with one positive and one negative number.

Question 21: Arrays: Given an array, find 3 elements such that [a + b + c] = 0. Find all the 3 unique elements.

Question 22: Arrays: Check if 3 consecutive odds exist

Question 23: Arrays: Given an integer array, find the maximum product made from continuous elements in that array.

Question 24: Arrays: Longest Increasing Subsequence

Question 25: Arrays: Given an array, find the majority element

Question 26: Arrays: Merge sorted array inplace

Question 27: Arrays: Find whether an array is subset of another array

Question 28: Arrays: Find a triplet that sum to a given value

Question 29: Arrays: Rain water trapping

Question 30: Arrays: Find triplet with minimum sum

Question 31: Arrays: Given an array of non repeating numbers and a key, find all the unique combinations in that array

Question 32: Arrays: Three way partitioning of an array around a given range

Question 33: Arrays: Minimum swaps required to bring all elements less than or equal to k together

Question 34: Arrays: Get minimum number of merge operations to make an array palindrome

Question 35: Arrays: Find the median of 2 sorted arrays of same size

Question 36: Arrays: Program to check if an Array is Palindrome or not

Question 37: Sort an array of 0s, 1s and 2s in C

Question 38: Given an array, the difference between the elements is one, find if the “key” element is present or not.

Matrix

Question 1: Matrix: Given a matrix of m x n elements , print all elements of the matrix in spiral order 

Question 2: Matrix: Given a 2D Matrix and a key element, search and return if element is present or not

Question 3: Matrix: Find median in a row wise sorted matrix

Question 4: Matrix: Find a row with maximum number of 1’s in a binary matrix

Question 5: Matrix: Given a m x n matrix, if an element is 0, set its entire row and column to 0

Question 6: Matrix: Given a positive integer n, generate a square matrix filled with elements from 1 to n^2 in spiral order

Question 7: Matrix: Find pair with maximum sum in the matrix.

Question 8: Matrix: Given an n x n 2D matrix rotate it by 90 degrees

Question 9: Matrix: Kth smallest element in a sorted matrix

Question 1o: Matrix: Get the common elements in all row of a matrix.

Strings

Question 1: Strings: Reverse a string

Question 2: Strings: Remove all consecutive duplicates from the string

Question 3: Strings: Print all the duplicates in a string

Question 4: Strings: Given a string convert into its equivalent ASCII form

Question 5: Strings: Program to check if strings are rotations of each other or not

Question 6: Strings: Second most repeated word in a sequence

Question 7: Strings: Minimum Number of Swaps to Make the Binary String Alternating

Question 8: Strings: Given a string find the longest Palindromic Substring

Question 9: Strings: Longer Contiguous Segments of Ones than Zeros

Question 1o: Strings: Given a string, print all the subsequence

Question 11: Strings: Permutations of a given string

Question 12: Strings: Divide binary string into sub strings with equal number of 0s and 1s.

Question 13: Strings: Given a sentence and maxWidth. Arrange the text in such a way that each line has exactly maxWidth characters

Question 14: Strings: Min Edit Distance

Question 15: Strings: Longest Substring Of All Vowels in Order

Question 16: Strings: Check balanced parenthesis

Question 17: Strings: Check if it is possible to re-arrange characters in a string, such a way that no two adjacent are same

Question 18: Strings: Rabin Karp algorithm 

Question 19: Strings: Knuth Morris Pratt String matching algorithm 

Question 2o: Strings: Convert a string into its mobile numeric keypad

Question 21: Strings: Get the minimum number of inversions needed to make an expression balanced

Question 22: Strings: Given a string return all the substring that is a palindrome

Question 23: Strings: Count the number of string in 2D character array

Question 24: Strings: Given 2D matrix and a word, find if the word exists in the grid

Question 25: Strings: Boyer Moore algorithm

Question 26: Strings: Convert Roman Numerals to Decimal

Question 27: Strings: Longest Common Prefix

Question 28: Strings: Minimum number of flips to make binary string alternate

Question 29: Strings: Minimum swaps required for bracket balancing

Question 3o: Strings: Find the first repeated word in a string

Question 31: Strings: Find the longest common subsequence between two strings.

Question 32: Strings: Given a string of integers, restore all valid IP addresses

Question 33: Strings: Smallest distinct window

Question 34: Strings: Check if it is possible to re-arrange characters in a string, such a way that no two adjacent are same

Question 35: Strings: Check if Word Equals Summation of Two Words

Question 36: Strings: Group Anagrams

Question 37: Strings: Minimum Window Substring

Question 38: Strings: Remove all consecutive duplicates from the string

Question 39: Strings: Wildcard Matching

Question 4o: Strings: Longest Prefix Suffix

Question 41: Strings: Find minimum operations required to transform a string into another string

Question 42: Strings: Given 2 strings, check if they are isomorphic strings

Question 43: Strings: Recursively print all sentences that can be formed from list of word lists

Question 44: Strings: Number of Different Integers in a String

Searching & Sorting

Question 1: Searching & Sorting: Find the first and last occurrence of an element

Question 2: Searching and Sorting: Get the fixed point in an array

Question 3: Searching & Sorting: Given an array sorted in ascending order and is rotated at some pivot, given a target value to search, if found in the array return its index

Question 4: Searching & Sorting: Calculate the square of a number and also check if that number is even or odd using bitwise operator.

Question 5: Searching and Sorting: Maximum and minimum of an array using minimum number of comparisons

Question 6: Searching and Sorting: Binary search on an array that is in descending order

Question 7: Searching and Sorting: Order-Agnostic Binary Search

Question 8: Searching and Sorting: Find the majority element in the array

Question 9: Searching and Sorting: Search an array where adjacent differ by at most k

Question 1o: Searching and Sorting: Count all distinct pairs with difference equal to k

Question 11: Searching and Sorting: Given an array n integers and an integer key, are there four elements a, b, c, and d in the array such that a + b + c + d = key? Find all unique quadruplets in the array which gives the sum of key.

Question 12: Searching and Sorting: Maximum sum such that no two elements are adjacent

Question 13: Searching and Sorting: Given an array of n integers and an integer “key”, find three integers in the array such that the sum is closest to key.

Question 14: Searching and Sorting: Merge 2 sorted arrays

Question 15: Searching and Sorting: print all subarrays with 0 sum

Question 16: Searching and Sorting: Product of array except itself

Question 17: Searching and Sorting: Sort Integers by The Number of 1 Bits

Question 18: Searching and Sorting: Minimum number of swaps required to sort an array

Question 19: Searching and Sorting: Find the smallest and second smallest elements in an array

Question 2o: Searching and Sorting: Find the number of times a Sorted array is Rotated

Question 21: Searching and Sorting: Searching in a Nearly Sorted Array

Question 22: Searching and Sorting: Find the minimum element from an array that is sorted and is rotated

Question 23: Searching and Sorting: K-th Element of Two Sorted Arrays

Question 24: Searching and Sorting: Find Floor of an element in a Sorted Array

Question 25: Searching and Sorting: Find Ceil of an element in a Sorted Array

Question 26: Searching and Sorting: Find position of an element in an Infinite Sorted Array

Question 27: Searching and Sorting: Job Sequencing with deadline Problem

Question 28: Searching and Sorting: Find the missing number in Arithmetic Progression

Question 29: Searching and Sorting: Factorial Trailing Zeroes

Question 3o: Searching and Sorting: Find the index of first 1 in an infinite sorted array of 0s and 1s

Question 31: Searching and Sorting: Peak Element

Question 32: Searching and Sorting: Find maximum element in Bitonic Array

Question 33: Searching and Sorting: Given a set of distinct integers, nums, return all possible subsets in CPP

Question 34: Searching and Sorting: Search An Element in Bitonic Array

Question 35: Searching and Sorting: Get the rotation count in sorted rotated array

Question 36: Searching and Sorting: Count the number of 1’s in an array sorted in decreasing order.

LinkedList

Question 1: Linked List: Reverse Linked List iterative and recursive

Question 2: Linked List: Reverse Linked List in groups

Question 3: Linked List: Given a linked list, check if it has a cycle in it, solution in C++

Question 4: Linked List: Rotate linked list by k nodes

Question 5: Linked List: Given a linked list, if it has a cycle, get the node where the cycle begins else return NULL.

Question 6: Linked List: Given a linked list with duplicates, remove the nodes with duplicates and keep only distinct numbers

Question 7: Linked List: Remove duplicates from an unsorted linked list

Question 8: Linked List: Move last element to front of a given Linked List

Question 9: Linked List: Add 1 to the linked list

Question 1o: Linked List: Given two non empty Linked List with non negative numbers, and numbers are stored in reverse order having single digit.

Question 11: Linked List: Find Intersection of Two Linked Lists

Question 12: Linked List: You are given a linked list and a key “x”, partition the list in such a way that, all the nodes less than “x” comes before the nodes greater than or equal to “x”

Question 13: Linked List: Given an unsorted linked list, sort the list using merge sort

Question 14: Linked List: Reverse Linked List given 2 points m and n

Question 15: Linked List: Find middle element in Linked List

Question 16: Linked List: Perform below operations on Circular Singly Linked List

Question 17: Linked List: Split circular Linked List into two halves

Question 18: Linked List: Program to Check if a Singly Linked List is Palindrome

Question 19: Linked List: Deletion from a Circular Linked List

Question 2o: Linked List: Reverse a Doubly Linked List

Question 21: Linked List: Find pairs with a given sum in a DLL.

Question 22: Linked List: Count triplets in a sorted DLL whose sum is equal to given value “k”.

Question 23: Linked List: Sort a “k”sorted Doubly Linked list

Question 24: Linked List: Rotate Doubly linked list by N nodes

Question 25: Linked List: Rotate a Doubly Linked list in group of Given Size

Question 26: Linked List: Merge two sorted linked lists and return it as a new list

Question 27: Linked List: Given linked list swap Nodes in Pairs

Question 28: Linked List: Flatten a Linked List

Question 29: Linked List: Given a linked list such that each node contains an additional random pointer which could point to any node in the list or null. Return the deep copy of the list

Question 3o: Linked List: Merge k sorted linked lists and return it as one sorted list in C++

Question 31: Linked List: Multiply two numbers represented by Linked Lists

Question 32: Linked List: Delete nodes which have a greater value on right side using recursion

Question 33: Linked List: Segregate even and odd nodes in a Linked List

Question 34: Linked List: Given a linked list Remove Nth Node From End of List

Question 35: Linked List: Odd Even Linked List

Binary Trees

Question 1: Binary Trees: Level Order Traversal

Question 2: Binary Trees: Display Reverse Level Order Traversal by using queue

Question 3: Binary Trees: Height or Max depth of a BTree

Question 4: Binary Trees: Diameter of a Binary Tree

Question 5: Binary Trees: Convert a binary tree to its Mirror Tree

Question 6: Binary Trees: Perform InOrder traversal on a Binary Tree by without Recursion

Question 7: Binary Trees: Perform PreOrder traversal on a Binary Tree by without Recursion

Question 8: Binary Trees: Perform PostOrder traversal on a Binary Tree by without Recursion

Question 9: Binary Trees: Left view and right view of a Binary Tree

Question 1o: Binary Trees: Check if Binary Tree is Foldable Tree

Question 11: Binary Trees: Top view of a binary tree

Question 12: Binary Trees: Bottom view of binary Tree

Question 13: Binary Trees: Spiral order or Zigzag traversal of a Binary Tree

Question 14: Binary Trees: Check if binary tree is a height balanced tree?

Question 15: Binary Trees: Diagonal Traversal of a Binary tree

Question 16: Binary Trees: Boundary Traversal of Binary Tree

Question 17: Binary Trees: Get Maximum width of Binary Tree

Question 18: Binary Trees: Convert Binary Tree to DLL

Question 19: Binary Trees: Convert Binary tree into Sum tree

Question 2o: Binary Trees: Construct Binary Tree from preorder and inorder traversal

Question 21: Binary Trees: Minimum swap required to convert binary tree to binary search tree

Question 22: Binary Trees: Check if binary tree is a sum tree

Question 23: Binary Trees: Check if all Leaf Nodes are at same level in Binary tree

Question 24: Binary Trees: Find Duplicate Subtrees

Question 25: Binary Trees: Check if Two Trees are Mirror Structure to each other

Question 26: Binary Trees: Get Sum of all nodes formed from Root to Leaf Path

Question 27: Binary Trees: Check if a given graph is tree or not

Question 28: Binary Trees: Find largest subtree sum in a tree

Question 29: Binary Trees: Maximum Sum of nodes in Binary tree such that no two are adjacent

Question 3o: Binary Trees: Print all the paths from root node to leaf node

Question 31: Binary Trees: Lowest Common ancestor of a Binary Tree.

Question 32: Binary Trees: Print the nodes at k distance from the root of a binary tree

Question 33: Binary Trees: Kth Ancestor of a Tree Node

Question 34: Binary Trees: Find Duplicate Subtrees

Question 35: Binary Trees: Check if two Binary Trees are Isomorphic

 

Binary Search Trees

Question 1: Binary Search Trees: Find a value in a BST

Question 2: Binary Search Trees: Deletion of a node in a BST

Question 3: Binary Search Trees: Find min and max value in a BST

Question 4: Binary Search Trees: Find the Inorder predecessor and successor for a given key in BST

Question 5: Binary Search Trees: A program to check if a binary tree is BST or not

Question 6: Binary Search Trees: Convert a BST into greater sum tree

Question 7: Binary Search Trees: LCA in a BST

Question 8: Binary Search Trees: Construct BST from preorder traversal

Question 9: Binary Search Trees: Convert Binary Tree into Binary Search Tree.

Question 1o: Binary Search Trees: Convert a normal BST into a Balanced BST

Question 11: Binary Search Trees: Merge Two balanced BST

Question 12: Binary Search Trees: Kth Largest Element in a BST

Question 13: Binary Search Trees: Kth smallest Element in a BST

Question 14: Binary Search Trees: Return the sum of given range in BST.

Question 15: Binary Search Trees: Get the Shortest distance between two nodes in BST

Question 16: Binary Search Trees: Count the number of BST nodes that lie in a given range.

Question 17: Binary Search Trees: Convert sorted DLL to Balanced BST

Question 18: Binary Search Trees: Find triplet sum in BST

Question 19: Binary Search Trees: Check if the pre-order is a valid BST

Question 2o: Binary Search Trees: Check if the BST has a dead end

Question 21: Binary Search Trees: Correct a BST where 2 nodes are swapped

Question 22: Binary Search Trees: Flatten BST to sorted list

 

Greedy

Question 1: Greedy: Activity Selection Problem

Question 2: Greedy: Job Sequencing with deadline Problem

Question 3: Greedy: Remove duplicates from a string

Question 4: Greedy: Add elements in an array so the sum is equal to the given range

Question 5: Greedy: Fractional knapsack tutorial with implementation

Question 6:

Question 7: Greedy: Remove k digits from an number to make it a smallest integer.

Question 8: Greedy: Get the minimum platforms needed to avoid delay in the train arrival.

Question 9: Greedy: Check if the string is a substring of another string

Question 1o: Greedy: Remove overlapping intervals.

Question 11: Greedy: Plant n flowers in flower bed

Question 12: Greedy: Maximum meetings in one room

Question 13: Greedy: Distribute Candy

Question 14: Greedy: Shuffle array so that one array element is greater than other array element

Question 15: Greedy: Schedule task efficiently

Question 16: Greedy: Partition characters

Question 17: Greedy: Maximum sum of absolute difference of an array

Question 18: Greedy: Juice change

Question 19: Greedy: Given a string, split into balanced strings.

Question 2o: Greedy: Perform operations on a broker calculator

Question 21: Greedy: Add minimum to make parentheses valid.

Question 22: Greedy: Remove covered intervals.

Question 23:

Question 24: Greedy: Reduce the array size to the half

Question 25: Greedy: Connect ropes with minimum cost.

Question 26: Dijkstra’s Algorithm

Question 27:

Question 28: Kruskal’s algorithm

Question 29: Greedy: Connect ropes with minimum cost.

Question 3o:

Question 31:

Question 32: Greedy: Find maximum sum possible equal sum of three stacks

BackTracking

Question 1: Backtracking: Partition string into its palindrome

Question 2: Backtracking: Letter Combinations of a Phone Number

Question 3: Backtracking: Solve Sudoku

Question 4: Backtracking: Check if the given board is valid Sudoku or not

Question 5: Backtracking: N-Queens

Question 6: Backtracking: Given an input string (s) and a pattern (p), implement regular expression matching with support for ‘.’ and ‘*’

Question 7: BackTracking: Given a collection of numbers that might contain duplicates, return all possible unique permutations

Question 8: Backtracking: You are given an array with repeated elements and a key element, find all unique combination to the key

Question 9: Backtracking: Get the k combination from an array of 1 to n

Question 1o: Backtracking: Given array of integers that might contain duplicates, return all the subsets

Question 11: Backtracking: Find combination sum of k numbers that sum up to n

Question 12: Backtracking: Given a collection of candidate numbers and a key, find all unique combinations in candidates where the candidate numbers sums to target

Question 13: Backtracking: Letter case permutation

Question 14: Backtracking: Return the number of queens possible in a chessboard

Question 15: Backtracking: Get the sequential digits from the given range

Question 16: Backtracking: Partition to K Equal Sum Subsets

Question 17: Backtracking: Get maximum sum in a matrix

Brute Force:

Question 1: Given an array of integers in ascending order, return index of the two numbers such that they add up to a specific key provided.

 

HashMap Technique:

Question 1: Given an array of integers in ascending order, return index of the two numbers such that they add up to a specific key provided.

 

Top-Down and/or Bottom Up approach

 

Question 1: Count the number of ways a baby can reach the nth stair taking 1 or 2 steps at a time in C language.