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The % sigil is only used when referring to the hash as a whole, such as when asking for keys %phone_book. The list of keys and values can be extracted using the built-in functions keys and values, respectively. So, for example, to print all the keys of a hash:
Maps are data structures that associate a key with an element. This lets the map be very flexible. If the key is the hash code of the element, the Map is essentially a Set. If it's just an increasing number, it becomes a list. Examples of Map implementations include java.util.HashMap, java.util.LinkedHashMap, and java.util.TreeMap.
Another very simple implementation technique, usable when the keys are restricted to a narrow range, is direct addressing into an array: the value for a given key k is stored at the array cell A[k], or if there is no mapping for k then the cell stores a special sentinel value that indicates the lack of a mapping. This technique is simple and ...
A small phone book as a hash table. In computer science, a hash table is a data structure that implements an associative array, also called a dictionary or simply map; an associative array is an abstract data type that maps keys to values. [3]
Keys are unique identifiers which map to particular values, which in turn can be anything from addresses, to documents, to arbitrary data. [2] Responsibility for maintaining the mapping from keys to values is distributed among the nodes, in such a way that a change in the set of participants causes a minimal amount of disruption.
Linear probing is a component of open addressing schemes for using a hash table to solve the dictionary problem.In the dictionary problem, a data structure should maintain a collection of key–value pairs subject to operations that insert or delete pairs from the collection or that search for the value associated with a given key.
For ordered access as defined by the java.util.NavigableMap interface, java.util.concurrent.ConcurrentSkipListMap was added in Java 1.6, [1] and implements java.util.concurrent.ConcurrentMap and also java.util.concurrent.ConcurrentNavigableMap. It is a Skip list which uses Lock-free techniques to make a tree
A minimal perfect hash function F is order preserving if keys are given in some order a 1, a 2, ..., a n and for any keys a j and a k, j < k implies F(a j) < F(a k). [9] In this case, the function value is just the position of each key in the sorted ordering of all of the keys.