POJ 1503 大整数

之前做的大整数，都是一位一位操作。

优化方案：压缩方案。

模板： + - *  操作符重载

#include<cstdio>

#include<iostream>

#include<cmath>

#include<algorithm>

#include<cstring>

#include<string>

#include<vector>

using namespace std;

struct bigint{ // only positive number;

    static const int BASE=;

    static const int WIDTH=;

    vector<int> s;

    //value

    bigint(long long num=){ *this = num;}

    bigint operator = (long long num){

        s.clear();

        do{

            s.push_back(num%BASE);

            num/=BASE;

        }while(num>);

        return *this;

    }

    bigint operator = (const string& str){

        s.clear() ;

        int x,len = (str.length()-)/WIDTH + ;

        for(int i=;i<len;i++){

            int end = str.length() - i*WIDTH;

            int start = max(,end - WIDTH);

            sscanf(str.substr(start,end-start).c_str(),"%d",&x);

            s.push_back(x);

        }

        return *this;

    }

    //input&output

    friend ostream& operator << (ostream &out, const bigint& x){

        out << x.s.back();

        for(int i=x.s.size()-;i>=;i--){

            char buf[];

            sprintf(buf,"%08d",x.s[i]);

            for(int j=;j<strlen(buf);j++) out << buf[j];

        }

        return out;

    }

    friend istream& operator >>(istream &in, bigint& x){

        string s;

        if(!(in>>s)) return in;

        x=s;

        return in;

    }

    //compare

    bool operator < (const bigint& b) const {

        if(s.size()!=b.s.size()) return s.size() < b.s.size();

        for(int i=s.size()-;i>=;i++) if(s[i]!=b.s[i]) return s[i] < b.s[i];

        return false;//equal

    }

    bool operator > (const bigint& b) const {return b < *this;}

    bool operator <= (const bigint& b) const {return !(b < *this);}

    bool operator >= (const bigint& b) const {return !(*this < b);}

    bool operator != (const bigint& b) const {return b < *this || *this < b;}

    bool operator == (const bigint& b) const {return !(b < *this) && !(*this < b);}

    //calculate

    bigint operator +(const bigint& b) const {

        bigint c;

        c.s.clear();

        for(int i=,g=;;i++){

            if(g== && 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;

    }

    bigint operator +=(const bigint& b){

        *this = *this + b;

        return *this;

    }

    bigint operator -(const bigint& b) const {

        bigint c;

        c.s.clear();

        for(int i=,g=;;i++){

            if(g== && 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];

            x+=BASE;

            c.s.push_back(x%BASE);

            g = x/BASE - ;

        }

        return c;

    }

    bigint operator * (const bigint& b) const {

        bigint c;

        c.s.clear();

        bigint g=;

        for(int i=;;i++){

            if(g.s.size()== && i>=s.size()+b.s.size()-) break;

            bigint x;

            x.s.clear() ;

            for(int j=;j<g.s.size();j++) x.s.push_back(g.s[j]);

            if(i<s.size()+b.s.size()-){

                for(int j = max( , i-(int)s.size()+);j<=min(i,(int)b.s.size()-);j++){

                    bigint t = (long long)b.s[j]*s[i-j];

                    x += t;

                }

            }

            c.s.push_back(x.s[]);

            g.s.clear();

            if(x.s.size()>) for(int j=;j<x.s.size();j++) g.s.push_back(x.s[j]);

        }

        return c;

    }

};

int main()

{

    //freopen("in.txt","r",stdin);

    bigint a;

    bigint b = ;

    bigint sum = ;

    while(cin>>a) {

        if(a==)

            break;

        sum +=a;

    }

    cout<< sum <<endl;

    return ;

}