摘要：1 public class Solution { 2 public ArrayList> threeSum(int[] num) { 3 if(num == null) 4 return null; 5 6 Arrays.sort(num); 7 HashSet> set = new HashSet>(); 8 9 for(int i = 0; i tmp = new ArrayList();17 tmp.add(nu... 阅读全文

摘要：Visitor:Represent an operation to be performed on the elements of an object structure. Visitor lets you define a new operation without changing the classes of the elements on which it operates. 阅读全文

摘要：Memento:Without violating encapsulation, capture and externalize an object's internal state so that the object can be restored to this state later. 阅读全文

摘要：Mediator:Define an object that encapsulates how a set of objects interact. Mediator promotes loose coupling by keeping objects from referring to each other explicitly, and it lets you vary their interaction independently. 阅读全文

摘要：Interpreter:Given a language, define a representation for its grammar along with an interpreter that uses the representation to interpret sentences in the language. 阅读全文

摘要：Prototype: Specify the kinds of objects to create using a prototypical instance, and create new objects by copying this prototype. 阅读全文

摘要：Builder:Separate the construction of a complex object from its representation so that the same construction process can create different representations. 阅读全文

摘要：Chain of Responsibility:Avoid coupling the sender of a request to its receiver by giving more than one object a chance to handle the request. Chain the receiving objects and pass the request along the chain until an object handles it. 阅读全文

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摘要：Flyweight:Use sharing to support large numbers of fine-grained objects efficiently. 阅读全文

摘要：The Bridge Pattern:Decouple an abstraction from its implementation so that the two can vary independently. 阅读全文

摘要：The Proxy Patternprovides a surrogate or placeholder for another object to control access to it. 阅读全文

摘要：The State Patternallows an object to alter its behavior when its internal state changes. The object will appear to change its class. 阅读全文

摘要：The Composite Patternallows you to compose objects into tree structures to represent part-whole hierarchies. Composite lets clients treat individual objects and compositions of objects uniformly. 阅读全文

摘要：The Iterator Pattern provides a way to access the elements of an aggregate object sequentially without exposing its underlying representation. 阅读全文

摘要：The Template Method Patterndefines the skeleton of an algorithm in a method, deferring some steps to subclasses. Template Method lets subclasses redefine certain steps of an algorithm without changing the algorithm's structure. 阅读全文

摘要：The Facade Patternprovides a unified interface to a set of interfaces in a subsystem. Facade defines a higher-level interface that makes the subsystem easier to use. 阅读全文

摘要：The Adapter Patternconverts the interface of a class into another interface the clients expect. Adapter lets classes work together that couldn't otherwise because of incompatible interfaces. Object Adapter v.s. Class Adapter 阅读全文

摘要：The Command Patternencapsulates a request as an object, thereby letting you parameterize other objects with different requests, queue or log requests, and support undoable operations. 阅读全文

摘要：The Singleton Patternensures a class has only one instance, and provide a global point of access to it. 阅读全文

摘要：The Abstract Factory Pattern provides an interface for creating families of related or dependent objects without specifying their concrete classes.implementation 阅读全文

摘要：The Factory Method Pattern defines an interface for creating an object, but lets subclasses decide which class to instantiate. Factory Method lets a class defer instantiation to subclasses.implementation 阅读全文

摘要：The Decorator Pattern attaches additional responsibilities to an object dynamically. Decorators provide a flexible alternative to subclassing for extendingfunctionality.implementation 阅读全文

摘要：The Observer Pattern defines a one-to-many dependency between objects so that when one object changes state, all of its dependents are notified and updated automatically. Observer Pattern = Publisher + Subcribersimplemenation: 阅读全文

摘要：1 /** 2 * Definition for singly-linked list with a random pointer. 3 * class RandomListNode { 4 * int label; 5 * RandomListNode next, random; 6 * RandomListNode(int x) { this.label = x; } 7 * }; 8 */ 9 public class Solution {10 public RandomListNode copyRandomList(RandomListN... 阅读全文