Top 50 Problems on Hash Data Structure asked in SDE Interviews Last Updated : 03 Jul, 2023 Improve Improve Like Article Like Save Share 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 array Find the frequency of each character in a string Find the first non-repeating character in a string Find the intersection of two arrays Find missing elements of a range Find the pair with given sum in an array Find the count of distinct elements in an array Count number of Distinct Substring in a String Print all distinct words from a paragraph Count all distinct pairs with difference equal to k Remove minimum number of elements such that no common element exist in both array Minimum insertions to form a palindrome with permutations allowed Find the only repetitive element between 1 to n-1 Remove duplicates from an array Medium Level Problems on Hash Data Structure Find the length of the longest consecutive sequence in an array Find all pairs with a given sum in an array Longest Consecutive Subsequence Find the first repeating element in an array Find the majority element in an array Find the subarray with given sum in an array Group all anagrams in an array of strings Longest sub-array having sum k Maximum length subarray with equal number of 0s and 1s Print all subarrays with 0 sum Sort an array according to the order defined by another array Range Queries for Frequencies of array elements Count subarrays having total distinct elements same as original array All unique triplets that sum up to a given value Smallest subarray with k distinct numbers Maximum possible difference of two subsets of an array Find the length of largest subarray with 0 sum Find Itinerary from a given list of tickets Find all pairs (a, b) in an array such that a % b = k Count the number of subarrays having a given XOR Hard Level Problems on Hash Data Structure Top k numbers in a stream Transform One String to Another using Minimum Number of Given Operation Find the longest substring with k unique characters Find the minimum window in a string containing all characters of another string Implement LRU Cache Longest subarray with sum divisible by k Count distinct elements in every window of size k Check if an array can be divided into pairs whose sum is divisible by k Clone a Binary Tree with Random Pointers Smallest window in a string containing all the characters of another string Length of longest strict bitonic subsequence Count maximum points on same line Phone directory Find number of Employees Under every Manager Palindrome Substring Queries Find All Duplicate Subtrees Like Article Suggest improvement Next Top 50 Problems on Heap Data Structure asked in SDE Interviews Share your thoughts in the comments Add Your Comment Please Login to comment...