A hash table is a data structure that stores key-value pairs. It uses a hash function to compute an index into an array of buckets or slots, from which the desired value can be found.
The hash function maps the key to an integer, which indicates the index in the array. Ideally, the hash function will assign each key to a unique bucket,
but most hash table designs employ an imperfect hash function, which might cause hash collisions where the hash function generates the same index for more than one key. Such collisions are typically accommodated in some way.
The time complexity of hash table operations such as search, insert, and delete is generally constant time or O(1), which means that the time required to perform an operation does not depend on the size of the hash table.
HASHMAP EXAMPLE CODE - JAVA
import java.util.HashMap;
public class Example {
public static void main(String[] args) {
// Create a new HashMap
HashMap map = new HashMap<>();
// Add some key-value pairs to the HashMap
map.put("apple", 1);
map.put("banana", 2);
map.put("cherry", 3);
// Retrieve a value from the HashMap
int value = map.get("banana");
// Print the value
System.out.println("The value of 'banana' is " + value);
}
}
In this example, we create a new HashMap object called 'map', that maps String keys to Integer values.
We then add some key-value pairs to the HashMap using the put() method. Finally, we retrieve the value associated with the key "banana" using the get() method and print it to the console(black screen).
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