题解 | 特殊乘法

#include<bits/stdc++.h>
using namespace std;

int chartonum(char a)
{
    return a-'0';
}

int main()
{
    string a,b;
    while(cin>>a>>b)
    {
        int len1 = a.length();
        int len2 = b.length();
        int sum = 0;
        for(int i = 0;i<len1;i++)
        {
            for(int j = 0;j<len2;j++)
            {
                sum += chartonum(a[i])*chartonum(b[j]);
            }
        }
        cout<<sum<<endl;
    }
    return 0;
}