Tsinghua special machine test multiplication Easy

The basic idea:

no;

 

key point:

no;

 

#include<iostream>
#include<vector>
#include<string>
using namespace std;

int charge(string a, string b) {
	int cnt=0;
	for (int i = 0; i < a.size(); i++) {
		for (int j = 0; j < b.size(); j++) {
			cnt += int(a[i] - '0')*int(b[j] - '0');
		}
	}
	return cnt;
}


int main() {
	string n,m;
	while (cin >> n >> m) {
		cout << charge(n, m)<<endl;
	}
	return 0;
}