Python

A dictionary is the only type of mapping in the Python language. The mapping type does not require a numeric value to be indexed to obtain the corresponding data item from a container. You can use the key (key) to map directly to the value, which is

http://blog.csdn.net/chenjinyu_tang/article/details/6732053 There is a Sys.path attribute inside. He is a list. In the case of Python importing a file or module in silence, he will first find the path to the module in the Sys.path. If not,The

File and input and output__builtins__ functions related to input and output in the module:Print ( value,... [, sep= ', end= ' \ n ', File=sys.stdout, Flush=false])file The default is to print to stdout , you can redirect to another placeSep

Given a binary tree, check whether it is a mirror of the itself (ie, symmetric around its center).For example, this binary tree is symmetric: 1 / 2 2/\/3 4 4 3But the following are not: 1 / 2 2 \ 3 3Note:Bonus points if

As a novice, I post the problems I have encountered.Error hint 1:typeerror:unbound method A () must is called with a instance as first argument (got nothing instead)1 class A: 2 def A (self): 3 Print ("I ' m a") 4 5 a.a ()Execution error

title :Given a sorted array of integers, find the starting and ending position of a Given target value.Your algorithm ' s runtime complexity must is in the order of O(log n).If the target is not a found in the array, return [-1, -1] .For

#-*-Coding:utf8-*-‘‘‘__author__ = ' [email protected] '24:swap Nodes in Pairshttps://oj.leetcode.com/problems/swap-nodes-in-pairs/Given a linked list, swap every, adjacent nodes and return its head.For example,Given 1->2->3->4, you should return the

I. SlicingSlicing operations are similar to sublist in Java, which is to get a sub-listFor example l=[' Zhangsan ', ' Lisi ', ' Wangwu '] then l[0, 2] means to start at index 0, until index 2 (excluding 2), exactly 2 elements. If the first index is

Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.For example, given n = 3, a solution set is:"((()))", "(()())", "(())()", "()(())", "()()()"The first thing that comes to mind when you see this

I. Calling a functionPython has built-in data type conversion functions, such as the Int () function to convert other data types to shaping>>> Int (' 123 ') 123>>> Int (12.34) 12>>> float (' 12.34 ') 12.34>>> str (1.23) ' 1.23 ' >>> Unicode (+) U ' >

#!/usr/bin/env python# Coding=utf-8import sockets = Socket.socket (Socket.af_inet,socket. Sock_stream) S.connect ((' www.sina.com.cn ',) s.send (' get/http/1.1\r\nhost:www.sina.com.cn\r\nconnection:close\ r\n\r\n ') buffer = []while true:d=s.recv (10

Calculate the run time of a Python programMethod 1Import datetimeStartTime = Datetime.datetime.now ()#long RunningEndtime = Datetime.datetime.now ()Print (endtime-starttime). secondsMethod 2Start = Time.time ()Run_fun ()End = Time.time ()Print

Python: Input and Output I. Output You can use print to add a string to output the specified text on the screen. For example, enter 'Liu yan liang' print 'LiuYanliang' printThe statement can also keep up with multiple strings separated by commas

Euler's plan (python) problem 6Sum square differenceProblem 6 The sum of the squares of the first ten natural numbers is,12 + 22 +... + 102 = 385 The square of the sum of the first ten natural numbers is,(1 + 2 +... + 10) 2 = 552 = 3025 Hence the

Euler's plan (python) problem 4Largest palindrome productProblem 4 A palindromic number reads the same both ways. The largest palindrome made from the product of two 2-digit numbers is 9009 = 91 × 99. Find the largest palindrome made from the

Python learning: custom object I. first look at a small program Class person: def _ init _ (self): print "new person" p = person (); It can be seen that the class custom object with the keyword is used in python, followed by a colon Then

Python learning: Scope I. first look at a small program K = 0; def changek (): k = 10; changek () print k Define a variable k Define a function changex Assign 10 to k in changex. Print x Execution result: 0 Note: k is a global

Python learning: String Slicing I. number of characters in the string Print "Hello" [0] indicates the first character in the output stringPrint "Hello" [-1] indicates the last character in the output string Ii. string segmentation Print "Hello" [1:

Use Python PIL and cPickle to read and save image databases   Computer Vision and machine learning tasks often deal with images. Mature OpenCV can be used in C ++ and a Python Image processing Library PIL (Python Image Library ), of course, PIL is

Python study Note 6-file and input/output, 6.1 file object All Python operations on files are based on operations on file objects. From the creation of file objects. Open () [file ()] provides an interface for initializing input and output. When