# [Leetcode] (python): 043-multiply Strings

Source: Internet
Author: User

Source of the topic

https://leetcode.com/problems/multiply-strings/

Given numbers represented as strings, return multiplication of the numbers as a string.

Note:the numbers can be arbitrarily large and is non-negative.

Test instructions Analysis

Input:two numbers expressed as String

Output:the multiply of the sums

Conditions: The number can be infinitely large, do two number multiplication

such as: "23650379502752" and "865382861454"

Result: "20466633088564555427721408"

Topic ideas

First converts two Str to a list of integers, then takes into account that the number of bits of the product is necessarily less than or equal to Len (str1) +len (str2), first Initializes a list of products of 0, and then follows the rule of multiplying the number of bits.

Attention:

1 The final result requires 0 of the large number to be removed, and if the result is 0 need to return the string "0"

2 Flip: Mul.reverse ()

AC Code (PYTHON)

`1_author_ ="YE"2 #-*-coding:utf-8-*-3 4 classsolution (object):5     defMultiply (self, NUM1, num2):6         """7 : Type Num1:str8 : Type Num2:str9 : Rtype:strTen         """ OneLen1 =Len (NUM1) ALen2 =Len (num2) -  -List1 = [0 forIinchrange (LEN1)] theList2 = [0 forIinchrange (len2)] -  -          forIinchRange (LEN1): -List1[len1-1-I] =Int (num1[i]) +          forIinchRange (len2): -List2[len2-1-I.] =Int (num2[i]) +  A         #print (LIST1,LIST2) at  -Mul = [0 forIinchRange (Len1 +len2)] -  -          forIinchRange (len2): -carry =0 -              forJinchRange (LEN1): inMul[i + j] = Mul[i + j] + carry + (List2[i] * list1[j])% 10 -  tocarry = (List2[i] * list1[j])//10 +  -                 ifMul[i + j] >= 10: thecarry = carry + Mul[i + j]//10 *Mul[i + j] = Mul[i + j]% 10 \$ Panax Notoginseng  -             ifCarry >0: theMul[i + len1] + =Carry +                 ifMul[i + len1] > 10: AMul[i + len1] = mul[i + len1]% 10 theCarry + = Mul[i + len1]//10 +  -index = len1 + len2-1 \$          whileIndex >=0: \$             ifMul[index] >0: -                  Break -Index-= 1 the  -         ifIndex + 1 < LEN1 +Len2:WuyiMul[index+1:] = [] the  - Mul.reverse () Wu  -s ="' About          forIinchRange (len (mul)): \$s + =str (mul[i]) -         ifs = ="': -s ='0' -         returns A  +STR1 ='12312' theSTR2 ='4234' -s =solution () \$  the Print(S.multiply (STR1,STR2))`

[Leetcode] (python): 043-multiply Strings

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