摘要：
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
摘要：
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
摘要：
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