In a array A of size 2N, there are N+1 unique elements, and exactly one of these elements is repeated N times. Return the element repeated N times. Ex ...

International Morse Code defines a standard encoding where each letter is mapped to a series of dots and dashes, as follows: “a” maps to “.-“, “b” map ...

Implement function ToLowerCase() that has a string parameter str, and returns the same string in lowercase. ExampleNo.1Input: “Hello” Output: “hello” ...

Every email consists of a local name and a domain name, separated by the @ sign. For example, in alice@leetcode.com, alice is the local name, and leet ...

Median is the middle value in an ordered integer list. If the size of the list is even, there is no middle value. So the median is the mean of the two ...

Given a string containing digits from 2-9 inclusive, return all possible letter combinations that the number could represent. A mapping of digit to le ...

You’re given strings J representing the types of stones that are jewels, and S representing the stones you have. Each character in S is a type of sto ...

Java语言准备了用于复制实例的clone方法。要想调用clone方法，被复制对象的类必须实现java.lang.Cloneable接口，不论是被复制对象的类实现java.lang.Cloneable接口还是其某个父类实现Cloneable接口，亦或是被复制对象的类实现了Cloneable接口的子接 ...

不根据类来生成实例，而是根据实例来生成新实例。 在开发过程中，有时候也会有“在不指定类名的前提下生成实例”的需求。例如，在以下情况下，就不能根据类来生成实例，而要根据现有的实例来生成新的实例。 (1) 对象种类繁多，无法将它们整合到一个类中时(2) 难以根据类生成实例时(3) 想解耦框架与生成的实例 ...

类图 Main.java1234567891011121314151617181920import activeobject.ActiveObject;import activeobject.ActiveObjectFactory;public class Main { public ...