Sunshine At Noon

摘要： Given an input string, reverse the string word by word.For example,Given s = "the sky is blue",return "blue is sky the".题解：用栈就行了代码： 1 class Solution {... 阅读全文

摘要： Implement next permutation, which rearranges numbers into the lexicographically next greater permutation of numbers.If such arrangement is not possibl... 阅读全文

摘要： The set[1,2,3,…,n]contains a total ofn! unique permutations.By listing and labeling all of the permutations in order,We get the following sequence (ie... 阅读全文

摘要： 发现自己不写总结真是件很恶劣的事情，好多学的东西没有自己总结都忘记了。所以决定从今天开始，学东西的时候一定跟上总结。我写的东西大多数是自己通俗的总结，不太喜欢写严格的定义或者证明，写了也记不住，欢迎指正。1. High Bias vs. High Variance High Bias:通常是因为模... 阅读全文

摘要： Given a binary tree, return theinordertraversal of its nodes' values.For example:Given binary tree{1,#,2,3}, 1 \ 2 / 3return[1,3,2].Note:Recursive solution is trivial, could you do it iteratively?解题：果然不能晚上做题，效率好低。看了讨论才学会的解法。设置一个指针next指向当前访问的节点，如果它不为空，就把它压栈，并且下一个访问它的左节点；如果它为空，就从栈顶一定是它的父... 阅读全文

摘要： Given a binary tree, return thepreordertraversal of its nodes' values.For example:Given binary tree{1,#,2,3}, 1 \ 2 / 3return[1,2,3].Not... 阅读全文

摘要： Given a linked list, determine if it has a cycle in it.Follow up:Can you solve it without using extra space?解题：开始进入一个误区，跟循环链表搞混了，其实这个环的开头可以不在head这里，例如... 阅读全文

摘要： 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

摘要： 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

摘要： 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