Hashing Data Structure Last Updated : 27 Sep, 2023 Read Discuss Courses DSA for Beginners Learn more about Hashing in DSA Self Paced Course Practice Problems on Hashing Top Quizzes on Hashing What is Hashing? 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. Let a hash function H(x) maps the value x at the index x%10 in an Array. For example if the list of values is [11,12,13,14,15] it will be stored at positions {1,2,3,4,5} in the array or Hash table respectively. Hashing Data Structure Topics: Introduction Standard problems on Hashing Introduction: Introduction to Hashing – Data Structure and Algorithm Tutorials What is Hashing? Index Mapping (or Trivial Hashing) Separate Chaining for Collision Handling Open Addressing for Collision Handling Double Hashing Load Factor and Rehashing Standard problem on Hashing: Easy: Find whether an array is subset of another array Union and Intersection of two linked lists Given an array A[] and a number x, check for pair in A[] with sum as x Maximum distance between two occurrences of same element in array Count maximum points on same line Most frequent element in an array Find the only repetitive element between 1 to n-1 How to check if two given sets are disjoint? Non-overlapping sum of two sets Check if two arrays are equal or not Find missing elements of a range Minimum number of subsets with distinct elements Remove minimum number of elements such that no common element exist in both array Find pairs with given sum such that elements of pair are in different rows Count pairs with given sum Count quadruples from four sorted arrays whose sum is equal to a given value x Sort elements by frequency Find all pairs (a, b) in an array such that a % b = k Group words with same set of characters k-th distinct (or non-repeating) element in an array. Medium: Find Itinerary from a given list of tickets Find number of Employees Under every Employee Longest subarray with sum divisible by k Find the largest subarray with 0 sum Longest Increasing consecutive subsequence Count distinct elements in every window of size k Design a data structure that supports insert, delete, search and getRandom in constant time Find subarray with given sum | Set 2 (Handles Negative Numbers) Implementing our Own Hash Table with Separate Chaining in Java Implementing own Hash Table with Open Addressing Linear Probing in C++ Minimum insertions to form a palindrome with permutations allowed Maximum possible difference of two subsets of an array Sorting using trivial hash function Smallest subarray with k distinct numbers Hard: Clone a Binary Tree with Random Pointers Largest subarray with equal number of 0s and 1s All unique triplets that sum up to a given value Palindrome Substring Queries Range Queries for Frequencies of array elements Elements to be added so that all elements of a range are present in array Cuckoo Hashing – Worst case O(1) Lookup! Count subarrays having total distinct elements same as original array Maximum array from two given arrays keeping order same Find Sum of all unique sub-array sum for a given array. Recaman’s sequence Length of longest strict bitonic subsequence Find All Duplicate Subtrees Find if there is a rectangle in binary matrix with corners as 1 Quick Links : ‘Practice Problems’ on Hashing Top 20 Hashing Technique based Interview Questions ‘Quizzes’ on Hashing ‘Videos’ on Hashing Recomended: Learn Data Structure and Algorithms | DSA Tutorial If you like GeeksforGeeks and would like to contribute, you can also write an article using write.geeksforgeeks.org or mail your article to review-team@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks. Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.