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Say you have an array for which the ith element is the price of a given stock on day i. If you were only permitted to complete at most one transaction 阅读全文
摘要：
Given an integer, write an algorithm to convert it to hexadecimal. For negative integer, two’s complement method is used. Note: All letters in hexadec 阅读全文
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Given two non-negative integers num1 and num2 represented as string, return the sum of num1 and num2. Note: 给定两个只含有数字字符串，将字符串中的数字和返回一个字符串。并且要求不能使用整数类库 阅读全文
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Given an array where elements are sorted in ascending order, convert it to a height balanced BST. 将一个有序的数组转换为一棵高度平衡的二叉树。这道题像中序遍历的逆过程。所以先找到数组中中间位置的值作为树 阅读全文
摘要：
Given a binary tree, you need to compute the length of the diameter of the tree. The diameter of a binary tree is the length of the longestpath betwee 阅读全文