Top 50 Problems on Hash Data Structure asked in SDE Interviews Last Updated : 03 Jul, 2023 Summarize Comments Improve Suggest changes Share Like Article Like Report Hashing is a technique or process of mapping keys, and values into the hash table by using a hash function. It is done for faster access to elements. The efficiency of mapping depends on the efficiency of the hash function used. To learn more about hashing and hashmaps, please refer to the Tutorial on Hashing. Given below are the most frequently asked interview questions on Hash:Easy Level Problems on Hash Data Structure Find whether an array is a subset of another arrayFind the frequency of each character in a stringFind the first non-repeating character in a stringFind the intersection of two arraysFind missing elements of a rangeFind the pair with given sum in an arrayFind the count of distinct elements in an arrayCount number of Distinct Substring in a StringPrint all distinct words from a paragraphCount all distinct pairs with difference equal to kRemove minimum number of elements such that no common element exist in both arrayMinimum insertions to form a palindrome with permutations allowedFind the only repetitive element between 1 to n-1Remove duplicates from an arrayMedium Level Problems on Hash Data Structure Find the length of the longest consecutive sequence in an arrayFind all pairs with a given sum in an arrayLongest Consecutive SubsequenceFind the first repeating element in an arrayFind the majority element in an arrayFind the subarray with given sum in an arrayGroup all anagrams in an array of stringsLongest sub-array having sum kMaximum length subarray with equal number of 0s and 1sPrint all subarrays with 0 sumSort an array according to the order defined by another arrayRange Queries for Frequencies of array elementsCount subarrays having total distinct elements same as original arrayAll unique triplets that sum up to a given valueSmallest subarray with k distinct numbersMaximum possible difference of two subsets of an arrayFind the length of largest subarray with 0 sumFind Itinerary from a given list of ticketsFind all pairs (a, b) in an array such that a % b = kCount the number of subarrays having a given XORHard Level Problems on Hash Data Structure Top k numbers in a streamTransform One String to Another using Minimum Number of Given OperationFind the longest substring with k unique charactersFind the minimum window in a string containing all characters of another stringImplement LRU CacheLongest subarray with sum divisible by kCount distinct elements in every window of size kCheck if an array can be divided into pairs whose sum is divisible by kClone a Binary Tree with Random PointersSmallest window in a string containing all the characters of another stringLength of longest strict bitonic subsequenceCount maximum points on same linePhone directoryFind number of Employees Under every ManagerPalindrome Substring QueriesFind All Duplicate Subtrees Comment More infoAdvertise with us Next Article Top 50 Problems on Hash Data Structure asked in SDE Interviews R RishabhPrabhu Follow Improve Article Tags : Hash DSA top-dsa-problems Practice Tags : Hash Similar Reads DSA Tutorial - Learn Data Structures and Algorithms DSA (Data Structures and Algorithms) is the study of organizing data efficiently using data structures like arrays, stacks, and trees, paired with step-by-step procedures (or algorithms) to solve problems effectively. Data structures manage how data is stored and accessed, while algorithms focus on 7 min read Quick Sort QuickSort is a sorting algorithm based on the Divide and Conquer that picks an element as a pivot and partitions the given array around the picked pivot by placing the pivot in its correct position in the sorted array. It works on the principle of divide and conquer, breaking down the problem into s 12 min read Merge Sort - Data Structure and Algorithms Tutorials Merge sort is a popular sorting algorithm known for its efficiency and stability. It follows the divide-and-conquer approach. It works by recursively dividing the input array into two halves, recursively sorting the two halves and finally merging them back together to obtain the sorted array. Merge 14 min read Data Structures Tutorial Data structures are the fundamental building blocks of computer programming. They define how data is organized, stored, and manipulated within a program. Understanding data structures is very important for developing efficient and effective algorithms. What is Data Structure?A data structure is a st 2 min read Bubble Sort Algorithm Bubble Sort is the simplest sorting algorithm that works by repeatedly swapping the adjacent elements if they are in the wrong order. This algorithm is not suitable for large data sets as its average and worst-case time complexity are quite high.We sort the array using multiple passes. After the fir 8 min read Breadth First Search or BFS for a Graph Given a undirected graph represented by an adjacency list adj, where each adj[i] represents the list of vertices connected to vertex i. Perform a Breadth First Search (BFS) traversal starting from vertex 0, visiting vertices from left to right according to the adjacency list, and return a list conta 15+ min read Binary Search Algorithm - Iterative and Recursive Implementation Binary Search Algorithm is a searching algorithm used in a sorted array by repeatedly dividing the search interval in half. The idea of binary search is to use the information that the array is sorted and reduce the time complexity to O(log N). Binary Search AlgorithmConditions to apply Binary Searc 15 min read Insertion Sort Algorithm Insertion sort is a simple sorting algorithm that works by iteratively inserting each element of an unsorted list into its correct position in a sorted portion of the list. It is like sorting playing cards in your hands. You split the cards into two groups: the sorted cards and the unsorted cards. T 9 min read Array Data Structure Guide In this article, we introduce array, implementation in different popular languages, its basic operations and commonly seen problems / interview questions. An array stores items (in case of C/C++ and Java Primitive Arrays) or their references (in case of Python, JS, Java Non-Primitive) at contiguous 4 min read Sorting Algorithms A Sorting Algorithm is used to rearrange a given array or list of elements in an order. For example, a given array [10, 20, 5, 2] becomes [2, 5, 10, 20] after sorting in increasing order and becomes [20, 10, 5, 2] after sorting in decreasing order. There exist different sorting algorithms for differ 3 min read Like