concise introduction to data structures using java

Java's class library is so many that many people don't understand it, and the result is that they always build their own wheels.The following summarizes some of the data structures in Java, plus some implementations of the analysis, as well as the memo.As for the complexity of time, the personal feel that the use of writing is not very useful. If you understand h

initialization capacity of the hashmap too high or load factor too low.Weakhashmap classWeakhashmap is an improved hashmap, which implements a "weak reference" to key, which can be recycled by GC if a key is no longer referenced externally.SummarizeIf it involves operations such as stacks, queues, and so on, you should consider using the list, for quick insertions, for deleting elements, should use LinkedList, and if you need to quickly randomly acce

In the development of the data will inevitably encounter, the system returns the collection of dictionaries, the collection of a dictionary, and then a dictionary or a dictionary or a collection of complex structure data ... Mjextension easily fix this kind of problem1. Workaround One:Example: There is a model for the post data in the best project, there is a col

1. HashMap Overview HashMap is an asynchronous implementation of the map interface based on a hash table (Hashtable is similar to HashMap, the only difference being that the method in Hashtalbe is thread-safe, that is, synchronous). This implementation provides all the optional mapping operations and allows NULL values and NULL keys to be used. This class does not guarantee the order of mappings, especially if it does not guarantee that the order is immutable. 2. Four points of attention on Has

which elements are maintained.HashSet: Set for quick find design. The object that is deposited into the hashset must define HASHCODE ().TreeSet: The set of the save order, the underlying tree structure. Use it to extract ordered sequences from the set.Linkedhashset: has hashset query speed, and internally uses the chain list to maintain the order of elements (the Order of insertions). The result is displayed in the order in which the elements are inserted when iterating through the set

in a dictionaryThe Dict () constructor can create a dictionary directly from the key-value pairDict ([' Tim ', 123), (' Tiny ', 234)]) >>>{' Tiny ': 234, ' Tim ': 123}Derivation creates a dictionary:{d2:d2+ ' @main. com ' for D2 in List (D.keys ()}}>>>{' Jack ': ' [email protected] ', ' Tom ': ' [email protected] '}Exercise: A key-value pair in a circular output dictionary:For Name,email in D.items ():Print (Name,email)4. CollectionEmpty collection: A = set () ※ to create an empty collection, y

....The following is mainly a hash table, called Hashtable or HashMap, the hash table can significantly improve the dictionary search speed, in short, it does not need to go through the key. For not a key name, it uses an algorithm to encode, the encoded value records the value of the address, well, like this picture below.　　Well, the above picture is based on the Ascⅱ code of each letter of the key name, and the actual situation is more complicated than this.Then we can do the corresponding ke

. The algorithm is then filtered up.Note: Up and down, filtering up is only compared with a parent node and stops filtering when it is smaller than the parent node.　　5. Complete Java Heap CodeFirst we need to know some of the main points of using arrays to represent heaps. If the index of the node in the array is x, then:The left child node of the node is 2*index+1,The right child node of the node is 2*inde

, card): Table.append (Card)ifTable.count (Card) >=2: whileTable.count (Card) >0:person.append (Table.pop ()) whileLen (hen)!=0 andLen (haa)! =0:#print "tab:", List (table)i = Hen.popleft ()#hen the cards first#print "Hen put", IRefreshtable (hen, i)#Hen Action#print "hen:", List (hen) #print "tab:", List (table)j = Haa.popleft ()#Haa after the card#print "Haa put", JRefreshtable (Haa, J)#haa Action#print "Haa:", List (HAA)#print "tab:", List (table)#print "Next Turn"

) Unordered array Delete (query + fill hole) O (N) Ordered array deletion (query + fill hole) O (N) Why not use data to solve everythingAn unordered array is inserted (O (1) time), and the query spends (O (N) time). An ordered array query spends (O (logn) time), but inserts a missing cost (O (N) time). And the deletion takes (O (N) time). So a data structur

Content:(1) Data type(2) operator(3) Branching structure1. Data type　　Basic data types in the Java language: Byte, short, int, long, float, double, Boolean, Char.1.1 Boolean type　　The types of false and true information described in the Java language are: Boolean.There are o

Arrays are the most widely used data storage structures. It is implanted in most programming languages.Basic knowledge of arrays in JavaCreate an arrayThey are treated as objects in Java, so you must use the new operator to create an array:Int[] Intarray;Defines a reference to an array Ingarray = new int[100]; Creates the array, and//sets int array to refer to it

Common data Structures in JavaCommon data structures are hash tables, linear lists, linked lists, and java.util packages with three important interfaces: List,set,map commonly used to implement basic data structuresHow the HashMap worksHashMap based on the hashing principle,

Java training two days before a piece of Java small meat Q: Small, Java data and algorithms which is important? To answer this question, I think it's a matter of solving a few common problems in life first.Big breasts and beautiful legs which is important?Who is the wife and wife to save before falling in the river?Who

This article does not speak of technology, the time to talk about the technology and popular there is a strange relationship between the driving force to learn something.1) technology and popularThe University of the Min data structure is not thick, rich content, but the complexity of the explanation of the problem is less, more difficult to understand, C is not very good, but the basic ideas are still there.Simple list of lists, arrays, stacks, queue

We write programs in Java, so what is the program? Program is the data structure + algorithm, that is, we write the program is essentially the operation of the data, digital, text, pictures, audio, video These are a form of information, we are programmed to manipulate the data, so as to achieve different functions. Whe

Java data structures and algorithms (Robert lafore) Chapter 4 /* Write a method in the queue class of the program job 4.1 For the queue. Java program (listing 4.4) to display the queue content. Note that this is not a simple display of the array content. It is required to display d