函数解法（包负数）

这道题板子题
不必多说
下面是代码

#include<bits/stdc++.h>
using namespace std;
void BNA(string s, string s1) {
	int mlen = max(s.size(), s1.size());
	vector<int> a(mlen, 0);
	vector<int> b(mlen, 0);
	vector<int> c(mlen + 1, 0);
	for (int i = 0; i < s.size(); i++) {
		a[i] = s[s.size() - 1 - i] - '0';
	}
	for (int i = 0; i < s1.size(); i++) {
		b[i] = s1[s1.size() - 1 - i] - '0';
	}
	for (int i = 0; i < mlen; i++) {
		c[i] += a[i] + b[i];
		c[i + 1] += c[i] / 10;
		c[i] %= 10;
	}
	int rlen = mlen;
	if (c[mlen] > 0) {
		rlen = mlen + 1;
	}
	string sum = "";
	for (int i = rlen - 1; i >= 0; i--) {
		sum += (c[i] + '0');
	}
	while (sum.size() > 1 && sum[0] == '0') {
		sum.erase(0, 1);
	}
	cout << sum << endl;
}
int main() {
    string s;
    string s1;
    cin>>s>>s1;
    BNA(s,s1);
    return 0;
}