![Hash Table
• How storing a value works (basically)
– I have a key and value I want to store
key = “Kurtz”
value = “ajkurtz@iuk.edu”
– Compute the hash value
hash = function(key)
– Store the key and the value
bucket[hash].add(key, value)](https://image.slidesharecdn.com/5-datastructureshashtable-150305165414-conversion-gate01/85/5-data-structures-hashtable-4-320.jpg)
![Hash Table
• How retrieving a value works (basically)
– I have a key and I want to get the value
key = “Kurtz”
– Compute the hash value
hash = function(key)
– Get the value
bucket[hash].get(key)
• If there is only one key/value pair in the bucket, return them.
• If there is more than one key/value pair look at each key in the bucket to find
the one that matches our search key and return that pair.](https://image.slidesharecdn.com/5-datastructureshashtable-150305165414-conversion-gate01/85/5-data-structures-hashtable-5-320.jpg)
5 data structures-hashtable
- 1. Hash Table • A hash table, or a hash map, is a data structure that associates keys with values. • The primary operation it supports efficiently is a lookup: given a key (e.g. a person's name), find the corresponding value (e.g. that person's telephone number). • It works by transforming the key using a hash function into a hash, a number that is used as an index in an array to locate the desired location ("bucket") where the values should be. • It’s possible that the hash function will return the same hash for two different keys. If that happens there will be more than one set of data in a given bucket.
- 2. Hash Table • Unique hash values...
- 3. Hash Table • Duplicate hash values...
- 4. Hash Table • How storing a value works (basically) – I have a key and value I want to store key = “Kurtz” value = “ajkurtz@iuk.edu” – Compute the hash value hash = function(key) – Store the key and the value bucket[hash].add(key, value)
- 5. Hash Table • How retrieving a value works (basically) – I have a key and I want to get the value key = “Kurtz” – Compute the hash value hash = function(key) – Get the value bucket[hash].get(key) • If there is only one key/value pair in the bucket, return them. • If there is more than one key/value pair look at each key in the bucket to find the one that matches our search key and return that pair.