题解 | 大整数相乘

import sys

def multiply(num1:str,num2:str):
    # 判别0
    if num1=='0' or num2=='0':
        return '0'
    
    m, n = len(num1), len(num2)
    res = [0]*(m+n)# 初始化一个全零数组用来存储

    for i in range(m-1, -1, -1):
        for j in range(n-1,-1, -1):
            mul = (ord(num1[i])-ord('0')) * (ord(num2[j])-ord('0'))
            
            p1 = i + j + 1
            p2 = i + j

            total = mul+res[p1]
            res[p1]=total%10
            res[p2] += total//10
    
    start = 0
    while start<len(res) and res[start]==0:
        start+=1
    return ''.join(map(str,res[start:]))


def main():
    num1, num2 = sys.stdin.readline().strip().split()
    print(multiply(num1, num2))


if __name__ == "__main__":
    main()