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Given a Binary Search Tree (BST), convert it to a Greater Tree such that every key of the original BST is changed to the original key plus sum of all 阅读全文
摘要：
Given an array of integers where 1 ≤ a[i] ≤ n (n = size of array), some elements appear twice and others appear once. Find all the elements of [1, n] 阅读全文
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1.1 概述 GC需要考虑的事：哪些内存需要回收，什么时候回收，如何回收 我们只要在程序出于运行期间的时候才会知道创建哪些对象，这部分内存和回收都是动态的，垃圾回收器所关注的就是这部分内存 1.2 对象已死吗？ 回收的前提就是判断对象是否还存活 1.2.1 引用计数算法 给一个对象添加一个计数器，若 阅读全文
摘要：
Given two binary trees and imagine that when you put one of them to cover the other, some nodes of the two trees are overlapped while the others are n 阅读全文