达叔

题目描述如下：Reverse digits of an integer.Example1: x = 123, return 321Example2: x = -123, return -321一目了然，知道了题目的意思了。。下面给出的我一开始的想法public int reverse(int num){ StringBuilder sb=new String

递归是非常神奇的方法，代码看起来很简洁。对二叉树的遍历和求最大深度可以用递归的方法，主要思路就是遍历左子树，再遍历右子树。如果左子树上面的结点，有右孩子，则调用右子树的方法；遍历到左子树的叶节点的时候，返回，开始遍历右子树。如果右子树上面的结点有左孩子，则调用左子树的方法，遍历到右子树的叶子结点的时候，程序结束。static void scanNodes(TreeNode root){ i

原题如下：Write a SQL query to get the second highest salary from the Employee table.+----+--------+| Id | Salary |+----+--------+| 1 | 100 || 2 | 200 || 3 | 300 |+----+--------+

突然发现leetcode出sql题了，找了道最简单的，找找自信。。题目如下：Table: Person+-------------+---------+| Column Name | Type |+-------------+---------+| PersonId | int || FirstName | varchar || LastNam

Suppose that a website contains two tables, the Customers table and the Orders table. Write a SQL query to find all customers who never order anything.Table: Customers.+----+-------+| Id | Na

The Employee table holds all employees including their managers. Every employee has an Id, and there is also a column for the manager Id.+----+-------+--------+-----------+| Id | Name | Salary |

前段时间忙数据交换，有一个多月没写java了。。找找手感，刷刷题吧。。去leetcode上挑了个简单的，题目是这样的。Given a string s consists of upper/lower-case alphabets and empty space characters ' ', return the length of last word in the strin

题目如下：Given a column title as appear in an Excel sheet, return its corresponding column number.For example: A -> 1 B -> 2 C -> 3 ... Z -> 26 AA -> 27 AB -> 28 可

题目是这样说的：Given an array of integers, every element appears twice except for one. Find that single one.Note:Your algorithm should have a linear runtime complexity. Could you implement it wit

class TreeNode{ TreeNode left; TreeNode right; int val; TreeNode(int val){ this.val=val; } static void scanNodes(TreeNode root){ if(root!=null){ System.out.println("this is node :"+root

题目描述是这样的：Given a binary tree, return the preorder traversal of its nodes' values.For example:Given binary tree {1,#,2,3}, 1 \ 2 / 3return [1,2,3].Note: R

题目要求如下：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 and the nodes have the same value.

题目的描述是这样的：Given an array of integers, every element appears three times except for one. Find that single one.Note:Your algorithm should have a linear runtime complexity. Could you implement it wit

题目如下Given an array of size n, find the majority element. The majority element is the element that appears more than ⌊ n/2 ⌋ times.You may assume that the array is non-empty and the majority