python 穷举指定长度的密码例子

本程序可根据给定的字符字典，穷举指定长度的所有字符串：

def get_pwd(str, num): if(num == 1): for x in str: yield x else: for x in str: for y in get_pwd(str, num-1): yield x+y strKey='abc'for x in get_pwd(strKey,3): print x

结果：

aaaaabaacabaabbabcacaacbaccbaababbacbbabbbbbcbcabcbbcccaacabcaccbacbbcbcccaccbccc

本程序占用内存小，生成速度快，欢迎尝试！！！

补充知识：Python 穷举法, 二分法 与牛顿-拉夫逊方法求解平方根的性能对比

穷举法, 二分法 与牛顿-拉夫逊方法求解平方根的优劣，从左到右依次递优。

经过测试，穷举法基本超过 1 分钟，还没有出数据；

二分法只要区区1秒不到就出结果了。

牛顿-拉夫逊是秒出，没有任何的停顿。

numberTarget =int(input('Please enter a number:'))numberSqureRoot = 0while(numberSqureRoot<abs(numberTarget)): if numberSqureRoot**2 >= abs(numberTarget): break numberSqureRoot = numberSqureRoot + 1if numberSqureRoot**2 != numberTarget: print('Your number %s is not a perfect squre, the square root is %s ' % ( numberTarget,numberSqureRoot) )else: if numberTarget < 0 : numberSqureRoot = -numberSqureRoot print('Your number %s is a perfect squre, the square root is %s ' % ( numberTarget, numberSqureRoot))print('now we begin to calculate the binary search...')numberTarget=int(input('Please enter the number for binary search...'))numberSqureRoot = 0lowValue = 0.0highValue=numberTarget*1.0epsilon = 0.01numberSqureRoot = (highValue + lowValue)/2while abs(numberSqureRoot**2 - numberTarget) >=epsilon: print('lowValue:%s, highValue:%s, currentValue:%s'%(lowValue,highValue,numberSqureRoot)) if numberSqureRoot**2<numberTarget: lowValue=numberSqureRoot else: highValue=numberSqureRoot numberSqureRoot = (lowValue+highValue) /2print('The number %s has the squre root as %s ' %(numberTarget,numberSqureRoot))print('now we begin to calculate the newTon search...')numberTarget=int(input('Please enter the number for newTon search...'))numberSqureRoot = 0epsilon = 0.01k=numberTargetnumberSqureRoot = k/2.0while( abs(numberSqureRoot*numberSqureRoot - k)>=epsilon): numberSqureRoot=numberSqureRoot-(((numberSqureRoot**2) - k)/(2*numberSqureRoot))print('squre root of %s is %s ' %(numberTarget,numberSqureRoot))

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