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原创 Python元组小结

Python的元组与列表类似，不同之处在于元组的元素不能修改。元组使用小括号，列表使用方括号。元组创建很简单，只需要在括号中添加元素，并使用逗号隔开即可。创建，访问，连接元组元组中只包含一个元素时，需要在元素后面添加逗号tup1 = ("abc", "Hello", "World", 1000, 2000)tup2 = (1, 2, 3, 4, 5 )tup3 = "a", "b", ...

2019-03-15 04:52:34 130

原创 Python列表小结

Python中的列表是最常用的数据类型，它可以作为一个方括号内的逗号分隔值出现，列表的数据项不需要具有相同的类型list1 = ["abc", "Hello", "World", 1000, 2000]list2 = [1, 2, 3, 4, 5]list3 = ["a", "b", "c", "d"]列表初始化list11 = range(10)lis

2019-03-14 09:07:27 169

原创 MIT单变量微积分笔记3——导数3

总结(ex)’ = e，ex在x=0处的导数是1指数函数的导数 (ax)’=axlna(lnx)’ = 1/x对数微分法，(lnu)’ = u’/u

2019-03-13 07:18:58 267

原创 MIT单变量微积分笔记2——导数2

幂函数的扩展：f(x) = xn的导数：f’(x) = nxn-1，n是整数，该公式对f(x) = xm/n, m,n 是整数同样适用。两端同时求导，由于y是x的函数，根据链式求导法则：隐函数的定义：本质上F(x,y)=0函数y=f(x)是一样的，但是在数学理论中，总有一些函数，人们已经证明它们的函数关系，但是还是无法表示成显函数的形式，就叫做隐函数。隐函数一般是一个含x,...

2019-03-13 07:11:33 424

原创 MIT单变量微积分笔记1——导数1

导数的概念：导数是高数中的重要概念，被应用于多种学科。从物理意义上讲，导数就是求解变化率的问题；从几何意义上讲，导数就是求函数在某一点上的切线的斜率。设函数y=f(x)在点x0的某个邻域内有定义，当自变量x在x0处取得增量Δx（点x0+Δx仍在该邻域内）时，相应地函数y取得增量Δy；如果Δy与Δx之比当Δx->0时的极限存在，则称函数y=f(x)在点x0处可导，并称这个极限为...

2019-03-13 06:56:00 581

原创 Python字符串小结——截取，运算符，前缀“r”，大小写，搜索，替换，分割

Python不支持单字符类型，单字符也是作为一个字符串使用s="hello world! abc"s1="hello world!\n abc"s2=r"hello world!\n abc"访问子字符串，可以用方括号来截取字符串print s[0]print s[1:4]print s[0:-1]print s[2:]hellhello world! abll...

2019-03-04 17:29:24 458

原创 [codewars][C++]Sum of a sequence

Your task is to make function, which returns the sum of a sequence of integers.The sequence is defined by 3 non-negative values: begin, end, step.If begin value is greater than the end, function s...

2019-02-22 15:44:27 274

原创 [codewars][python][C++]Mumbling

This time no story, no theory. The examples below show you how to write function accum:Examples:accum("abcd") -> "A-Bb-Ccc-Dddd"accum("RqaEzty") -> "R-Qq-Aaa-Eeee-Zzzzz-Tttttt-Yyyyyyy"acc...

2019-02-22 12:48:03 356

原创 [codewars][python][C++]Count the Digit

Take an integer n (n >= 0) and a digit d (0 <= d <= 9) as an integer. Square all numbers k (0 <= k <= n) between 0 and n. Count the numbers of digits d used in the writing of all the k*...

2019-02-21 10:50:56 326

原创 [codewars][python][C++]Even numbers in an array

Given an array of digitals numbers, return a new array of length number containing the last even numbers from the original array (in the same order). The original array will be not empty and will cont...

2019-02-20 13:12:42 165

原创 [codewars][python]IP Validation

Write an algorithm that will identify valid IPv4 addresses in dot-decimal format. IPs should be considered valid if they consist of four octets, with values between 0 and 255, inclusive.Input to the...

2019-02-19 17:16:35 320

原创 [codewars][python]Squares in a Rectangle

A rectangle can be split up into a grid of 1x1 squares, the amount of which being equal to the product of the two dimensions of the rectangle. Depending on the size of the rectangle, that grid of 1x1 ...

2019-02-19 16:50:56 178

原创 [codewars][python]Suitcase packing

Mr. Square is going on a holiday. He wants to bring 2 of his favorite squares with him, so he put them in his rectangle suitcase.Write a function that, given the size of the squares and the suitcase...

2019-02-19 14:29:33 281

原创 [codewars][python]Total amount of points

Our football team finished the championship. The result of each match look like "x:y". Results of all matches are recorded in the collection.For example: ["3:1", "2:2", "0:1", ...]Write a function...

2019-02-19 10:55:36 611

原创 [LeetCode][C#]Counting Bits

Given a non negative integer number num. For every numbers i in the range 0 ≤ i ≤ num calculate the number of 1's in their binary representation and return them as an array.Example 1:Input: 2Out...

2019-02-18 17:12:34 114

原创 [LeetCode][C#]Total Hamming Distance

The Hamming Distance between two integers is the number of positions at which the corresponding bits are different.Now your job is to find the total Hamming distance between all pairs of the given n...

2019-02-18 16:50:13 78

原创 [LeetCode][C#]Number of 1 Bits

Write a function that takes an unsigned integer and return the number of '1' bits it has (also known as the Hamming weight). Example 1:Input: 00000000000000000000000000001011Output: 3Explanat...

2019-02-18 16:37:39 148

原创 [LeetCode][C#]Power of Four

Given an integer (signed 32 bits), write a function to check whether it is a power of 4.Example 1:Input: 16Output: trueExample 2:Input: 5Output: false思路：从1开始依次乘以4，直到超过给定的值，即可判断。注意：乘4结...

2019-02-18 15:10:57 91

原创 js接收后台json数据的中文乱码问题

前台：javascript后台：servlet前台代码：放在head里面后台代码：response.setContentType("text/html;charset=UTF-8");

2016-09-09 17:12:29 2756

原创 mysql5.7的archive版本在win10下安装小记

一、下载网址：http://dev.mysql.com/downloads/mysql/下面找到zip archive的对应版本，我的系统是64bit，就下64bit的。大概是300多m的文件二、系统设置解压缩到想要安装的文件夹下环境变量path需要新增一个文件夹就是安装文件夹下的bin文件夹比如我解压到E:\MyWeb\mysql\mysql-5.7那么path增加的...

2016-08-24 20:10:13 429 1

原创 java dynamic web project的一个最简单的例子

环境条件：eclipse Version: Mars.2 Release (4.5.2)tomcat7.0.70 1.eclipse--file--new--other--找到 Dynamic web project给项目取个名字，比如nova。再选择配置的server，我用的是tomcat7.0.70。也可以预先就将server配置好，这里只需要下拉框就行。2.然后一...

2016-08-19 22:09:57 4696 2

原创 win10+tomcat7解压版安装小记

windows10系统，装tomcat做server。1.下载tomcat7，点击下图黄色部分的链接网址http://tomcat.apache.org/请记住如果要下载安装版就是这个32-bit/64-bit Windows Service Installer解压版是只需要下载对应系统的32位或者64的.zip文件32-bit Windows zip (pgp, md5, s...

2016-08-18 22:07:11 7029 2