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Givenn, how many structurally uniqueBST's(binary search trees) that store values 1...n?For example,Givenn= 3, there are a total of 5 unique BST's. 1 3 3 2 1 \ / / / \ \ 3 2 1 1 3 2 / / \ \ 2 1 ... 阅读全文
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Say you have an array for which theithelement is the price of a given stock on dayi.Design an algorithm to find the maximum profit. You may complete a... 阅读全文
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Reverse digits of an integer.Example1:x = 123, return 321Example2:x = -123, return -321解题：设定一个变量sum存放反转后的答案，每次取输入x的最后一位n，并用sum = sum*10+n更新sum。例如题设的数字123，初始sum为0，过程如下：取末尾的3，sum=3，x=12取末尾的2，sum=32，x=1取末尾的1，sum=321，x=0特别注意x一开始就是0的处理，直接返回0就可以了。代码： 1 class Solution { 2 public: 3 int reverse(int x) {... 阅读全文
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Given two binary trees, write a function to check if they are equal or not.Two binary trees are considered equal if they are structurally identical an... 阅读全文