python里大整数相乘相关技巧指南

>>> 2899887676637907866*17887789927883482773899435187258157415700236034169791337062588991638L

#!/usr/bin/env python#coding:utf-8#阿拉伯乘法def arabic_multiplication(num1,num2):  num_lst1 = [int(i) for i in str(num1)] #将int类型的123，转化为list类型的[1,2,3]，每个元素都是int类型  num_lst2 = [int(i) for i in str(num2)]  #两个list中整数两两相乘  int_martix = [[i*j for i in num_lst1] for j in num_lst2]  #将上述元素为数字的list转化为元素类型是str，主要是将9-->'09'  str_martix = [map(convert_to_str,int_martix[i]) for i in range(len(int_martix))]  #将上述各个list中的两位数字分开：['01','29','03']-->[0,2,0],[1,9,3]  martix = [[int(str_martix[i][j][z]) for j in range(len(str_martix[i]))] for i in range(len(str_martix)) for z in range(2)]  #计算阿拉伯乘法表的左侧开始各项和  sum_left = summ_left(martix)  #计算阿拉伯乘法表的底部开始各项和  sum_end = summ_end(martix)  #将上述两个结果合并后翻转  sum_left.extend(sum_end)  sum_left.reverse()  #取得各个和的个位的数字（如果进位则加上）  result = take_digit(sum_left)  #翻转结果并合并为一个结果字符串数值  result.reverse()  int_result = "".join(result)  print "%d*%d="%(num1,num2)  print int_result#将int类型转化为str类型，9-->'09'def convert_to_str(num):  if num<10:    return "0"+str(num)  else:    return str(num)#计算阿拉伯乘法表格左侧开始的各项之和def summ_left(lst):  summ = []  x = [i for i in range(len(lst))]  y = [j for j in range(len(lst[0]))]  sx = [i for i in x if i%2==0]  for i in sx:    s=0    j=0    while i>=0 and j<=y[-1]:      s = s+ lst[i][j]      if i%2==1:        j = j+1      else:        j = j      i = i-1    summ.append(s)  return summ#计算阿拉伯乘法表格底部开始的各项之和def summ_end(lst):  summ=[]  y = [j for j in range(len(lst[0]))]  ex = len(lst)-1  for m in range(len(y)):    s = 0    i=ex    j=m    while i>=0 and j<=y[-1]:      s= s+lst[i][j]      if i%2==1:        j = j+1      else:        j=j      i = i-1    summ.append(s)  return summ#得到各个元素的个位数，如果是大于10则向下一个进位def take_digit(lst):  tmp = 0  digit_list = []  for m in range(len(lst)):    lstm = 0    lstm = lst[m]+tmp    if lstm<10:      tmp = 0      digit_list.append(str(lstm))    else:      tmp = lstm/10      mm = lstm-tmp*10      digit_list.append(str(mm))  return digit_listif __name__=="__main__":  arabic_multiplication(469,37)