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1.定义 ReentrantLock是一种可重入锁，允许一个线程对同一个资源重复加锁，如果说是当一个线程调用一个锁的lock()方法，然后再次调用锁的lock()方法，当锁不支持可重入时，该线程会被自己所阻塞。该锁还能支持公平锁和非公平锁的选择，公平的意思就是将锁分配给等待锁时间最长的线程，这样可以 阅读全文
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Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list. 题目大意： 给一个排好序的LinkedLis 阅读全文
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Suppose an array sorted in ascending order is rotated at some pivot unknown to you beforehand.(i.e., [0,0,1,2,2,5,6] might become [2,5,6,0,0,1,2]). Yo 阅读全文
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Given a sorted array nums, remove the duplicates in-place such that duplicates appeared at most twice and return the new length. Do not allocate extra 阅读全文
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Given a set of distinct integers, nums, return all possible subsets (the power set). Note: The solution set must not contain duplicate subsets. Exampl 阅读全文
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Given a 2D board and a word, find if the word exists in the grid. The word can be constructed from letters of sequentially adjacent cell,where "adjace 阅读全文
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从Lock接口可以看出，Lock提供了许多synchronized关键字不具备的很多功能。 1.具备了获取锁和释放锁的可操作性，synchronized将锁的获取和释放固化了，一定是先获取再释放。假设存在场景需要先获取锁A，再获取锁B，再对A进行释放，最后再对B进行释放，那么synchronized 阅读全文
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1.定义 ThreadLocal是线程变量，就是说每一个线程都有对应的该变量副本，线程修改该变量时，线程与线程之间的变量是相互隔离的，互相并看不见。这个结构附带在线程上，一个线程可以根据ThreadLocal对象查询到绑定到该线程上的值。 2.主要方法 ThreadLocal的主要方法都是基于Thr 阅读全文
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Given an array with n objects colored red, white or blue, sort them in-place so that objects of the same color are adjacent, with the colors in the or 阅读全文
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Write an efficient algorithm that searches for a value in an m x n matrix.This matrix has the following properties: Integers in each row are sorted fr 阅读全文