这两天过了遍Lua，Lua的一个语言特性是支持尾递归，这是我接触的第一个支持尾递归的语言（尾递归优化）
尾递归，是尾调用的一种类型，后者更加准确，因为实际的正确尾递归（Proper Tail Recursion）是不涉及递归的。尾调用是指一个函数里的最后一个动作是一个函数调用的情形：即这个调用的返回值直接被当前函数返回的情形。这种情形下称该调用位置为尾位置。若这个函数在尾位置调用本身（或是一个尾调用本身的其他函数等等），则称这种情况为尾递归，是递归的一种特殊情形。尾调用不一定是递归调用，但是尾递归特别有用，也比较容易实现。
我们直接的来看一下Lua中尾调用：
function f(x)
| import re | |
| cctlds = ['AC','AD','AE','AF','AG','AI','AL','AM','AN','AO','AQ','AR','AS','AT','AU','AW','AX','AZ','BA','BB','BD',\ | |
| 'BE','BF','BG','BH','BI','BJ','BL','BM','BN','BO','BQ','BR','BS','BT','BV','BW','BY','BZ','CA','CC','CD',\ | |
| 'CF','CG','CH','CI','CK','CL','CM','CN','CO','CO','CR','CU','CV','CW','CX','CY','CZ','DE','DJ','DK','DM',\ | |
| 'DO','DZ','EC','EE','EG','EH','ER','ES','ET','EU','FI','FJ','FK','FM','FO','FR','GA','GB','GD','GE','GF',\ | |
| 'GG','GH','GI','GL','GM','GN','GP','GQ','GR','GS','GT','GU','GW','GY','HK','HM','HN','HR','HT','HU','ID',\ | |
| 'IE','IL','IM','IN','IO','IQ','IR','IS','IT','JE','JM','JO','JP','KE','KG','KH','KI','KM','KN','KP','KR',\ | |
| 'KW','KY','KZ','LA','LB','LC','LI','LK','LR','LS','LT','LU','LV','LY','MA','MC','MD','ME','MF','MG','MH',\ | |
| 'MK','ML','MM','MN','MO','MP','MQ','MR','MS','MT','MU','MV','MW','MX','MY','MZ','NA','NC','NE','NF','NG',\ |
| _escape_map = {ord('&'): '&', ord('<'): '<', ord('>'): '>'} | |
| _escape_map_full = {ord('&'): '&', ord('<'): '<', ord('>'): '>', | |
| ord('"'): '"', ord('\''): '''} | |
| # NB: this is a candidate for a bytes/string polymorphic interface | |
| def escape(s, quote=True): | |
| """ | |
| Replace special characters "&", "<" and ">" to HTML-safe sequences. | |
| If the optional flag quote is true (the default), the quotation mark |
| #heap sort | |
| #intruduction to algorithm | |
| import sys | |
| from math import floor | |
| def Max_Heapify(data,i): | |
| l = 2*i | |
| r = 2*i + 1 | |
| if l <= len(data) - 1 and data[l] > data[i]: | |
| largest = l |
| /*写多了Java和Python，写C++全是坑。。。。。:| */ | |
| #include <cstdio> | |
| #include <string> | |
| #include <iostream> | |
| #include <vector> | |
| #include <sstream> | |
| #include <cstdlib> | |
| #include <cassert> | |
| class Student |
| from sqlalchemy.exc import IntegrityError | |
| from flask import g, request, session, redirect, flash | |
| import urllib | |
| import urllib2 | |
| from app import models | |
| @app.route('/douban/login') | |
| def get_auth_code(): | |
| return redirect("https://www.douban.com/service/auth2/auth?client_id=0fb837361a070e2d2f28a5a24e152a87&redirect_uri=https://douping.sinaapp.com/auth&response_type=code") |
| #include <cstdio> | |
| #include <cstring> | |
| #include <iostream> | |
| using namespace std; | |
| void match_list(char * pattern, int match[] , size_t len) | |
| { | |
| memset(match, 0 ,sizeof(int)*len); |
| #C数组下标的实现 | |
| """ | |
| 其实一个例子就能说明，C中数组下标的实现方法。 | |
| ................ | |
| int array[4]; | |
| array[2] 和 2[array]是等价的。 | |
| ................ | |
| 2[array]，这是个什么玩意儿。 | |
| 2[array]等价于： |
| #代码来自Python 2.7 Lib/wsgiref/utils.py | |
| #__contains__判断一个字典中是否有key， 等同于has_key | |
| _hoppish = { | |
| 'connection':1, 'keep-alive':1, 'proxy-authenticate':1, | |
| 'proxy-authorization':1, 'te':1, 'trailers':1, 'transfer-encoding':1, | |
| 'upgrade':1 | |
| }.__contains__ | |
| def is_hop_by_hop(header_name): |
| //JavaScript : The Good Parts | |
| //闭包，存储数据 | |
| var memoizer = function (memo, formula) { | |
| var recur = function(n){ | |
| var result = memo[n]; | |
| if (typeof result !== 'number') { | |
| result = formula(recur, n); | |
| memo[n] = result; | |
| }; | |
| return result; |