A hash table is a data structure. It uses to store keys and values. The hash table does not allow to duplicate the keys. It allows to lookup the value based on the key.

Hash tables are used frequently in the database index, cache. The image shows the dictionary which build on top of the hash table. Hash collisions are practically unavoidable when hashing a random subset of a large set of possible keys. The following collision resolution strategy used for resolving the key collision.

  • Separate chaining
  • Open addressing
  • Linear probing
  • Double hashing
  • Hopscotch hashing
  • Robin Hood hashing

Hashtable section explains how to implement the Hashtable and various applications related with Hash operation.

Data structure problems
115 Hash Table implementation
A hash table is a data structure used to implement an associative array with keys and values.
116 Separate chaining
A hash table is a data structure used to implement an associative array. It is a structure that can map keys to values. A hash table uses a hash function to compute an index into an array of buckets, from which the desired value can be found.
117 Linear probing hash tables
Linear probing is a scheme in computer programming for resolving hash collisions of values of hash functions by sequentially searching the hash table for a free location
118 First Non Repeated characters
Write a program to find first non-repeating char on it using hashtable.
119 Intersection of Two given Arrays
Write a program to find intersection of two given Arrays using hash table.
120 Print BT vertically
Write a program to print the Binary tree vertically using hashtable.
121 Union of Array Lists
Write a program to find Intersection and union of ArrayLists.