Questions and Answers
What is the primary function of a hash function?
To map keys to hash values
What is the hash value of key x in the given hash function?
x mod N
What is the purpose of the hash table data structure?
To store records in a specific location
What is the relationship between the hash function and the hash table?
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What is a key in the context of hashing?
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What is the purpose of using a hash function in a hash table?
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What is a characteristic of the items stored in a hash table?
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What is the range of values that can be used to index items in a hash table?
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What is the term for the result of applying a hash function to a key?
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What is an advantage of using a hash table data structure?
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What are the two main factors that hashing depends on?
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What is a characteristic of a hash table data structure?
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Study Notes
Hashing Components
- Hashing consists of two major components: Hash function h and Hash Table Data Structure of size N.
Hash Function
- A hash function h maps keys (a identifying element of a record set) to a hash value or hash key.
- The hash value or hash key refers to a specific location in the Hash Table.
- Example of a hash function for integer keys: h(x) = x mod N.
- The result of the hash function, h(x), is called the hash value of key x.
Hash Table Data Structure
- A hash table is an array of fixed size containing keys, where records are not stored consecutively.
- Keys and entries are scattered throughout the array, with their place of storage calculated using the key and a hash function.
- A hash table combines the advantages of both arrays and trees.
Hash Function and Collision Resolution
- The two main factors in hashing are the hash function and collision resolution.
- The hash function applies to a key to produce a hashed key.
- A good hash function distributes keys uniformly across the array.
Table Size and Indexing
- Table size is a factor in hashing, with the array indexed from 0 to tablesize-1.
- Each stored item has a data member, called a key, used to compute the index value.
- Keys can be integers, strings, or other data types, such as a name or ID in an employee structure.
Hash Function and Mapping
- The mapping from a key to an index is called a hash function.
- The hash function determines the index value for storing and retrieving items from the hash table.
