刘汝佳大数模板（只含加法）

#include <bits/stdc++.h>
using namespace std;
struct BigInteger{
    static const int BASE = 100000000;
    static const int WIDTH = 8;
    vector<int> s;
    BigInteger(long long num=0) {*this = num;}
    BigInteger operator =(long long num){
        s.clear();
        do{
            s.push_back(num % BASE);
            num /= BASE;
        }while(num > 0);
        return *this;
    }
    BigInteger operator = (const string & str){
        s.clear();
        int x,len = (str.length()-1)/WIDTH + 1;
        for(int i=0;i<len;i++){
            int end = str.length()-i*WIDTH;
            int start =max (0,end - WIDTH);
            sscanf(str.substr(start,end-start).c_str(),"%d",&x);
            s.push_back(x);
        }
        return *this;
    }
    BigInteger operator + (const BigInteger& b) const {
        BigInteger c;
        c.s.clear();
        for(int i=0,g=0;;i++){
            if(g==0&&i>=s.size()&&i>=b.s.size()) break;
            int x=g;
            if(i<s.size()) x+=s[i];
            if(i<b.s.size()) x+=b.s[i];
            c.s.push_back(x%BASE);
            g=x/BASE;
        }
        return c;
    }
};
ostream& operator << (ostream &out,const BigInteger& x){
    out<<x.s.back();
    for(int i=x.s.size()-2;i>=0;i--){
        char buf[20];
        sprintf(buf,"%08d",x.s[i]);
        for(int j=0;j<strlen(buf);j++) out<<buf[j];
    }
    return out;
}
istream& operator >> (istream &in,BigInteger& x) {
    string s;
    if(!(in>>s)) return in;
    x=s;
    return in;
}
int main() {
	BigInteger x,y,p;
	cin>>x>>y;
	p=x+y;
	cout<<p<<endl;
	return 0;
}