高精度运算

struct High_accuracy
{
    int num[310];
    int siz;

    //初始化
    High_accuracy()
    {
        for( int i=0;i<310;i++ ) num[i]=0;
        siz=0;
    }

	//直接读入高精
    void read()
    {
        string s;
        cin>>s;
        siz=s.size();
        for( int i=1;i<=siz;i++ ) num[i]=( s[siz-i]-'0' );
    }

    //整型读入转化为高精
    void read( int x )
    {
        int dre=0;
        while( x )
        {
            num[++dre]=x%10;
            x/=10;
        }
        siz=dre;
    }

    //输出高精
    void print()
    {
        //前导0已经在各运算中省略
        for( int i=siz;i>=1;i-- ) cout<<num[i];
        cout<<"\n";
    }

    //高精加高精
    High_accuracy operator +( High_accuracy b )
    {
        High_accuracy ans;
        ans.siz=max( siz,b.siz );
        for( int i=1;i<=ans.siz;i++ )
        {
            ans.num[i]+=num[i]+b.num[i];
            if( ans.num[i] >= 10 ){ ans.num[i+1]+=1, ans.num[i]%=10; }
        }
        if( ans.num[ans.siz+1] ) ans.siz++;
        return ans;
    }

    //高精减高精
    High_accuracy operator -( High_accuracy b )
    {
        High_accuracy ans;
        ans.siz=1;//保证可以输出0
        for( int i=1;i<=siz;i++ )
        {
            int del=num[i]-b.num[i];
            if( del < 0 ){ num[i+1]-=1, del+=10; }
            ans.num[i]=del;
            if( del ){ ans.siz=i; }
        }
        return ans;
    }

    //高精乘高精(乘低精就转化为高精)
    High_accuracy operator *( High_accuracy b )
    {
        High_accuracy ans;
        for( int i=1;i<=siz;i++ )
        {
            for( int j=1;j<=b.siz;j++ )
            {
                int add=num[i]*b.num[j];
                ans.num[i+j-1]+=add;
                if( ans.num[i+j-1] >= 10 )
                {
                    ans.num[i+j]+=ans.num[i+j-1]/10;
                    ans.num[i+j-1]%=10;
                    ans.siz=max( ans.siz,i+j );
                }
                ans.siz=max( ans.siz,i+j-1 );
            }
        }
        return ans;
    }

    //高精除低精(竖式模拟)
    High_accuracy operator /( int b )
    {
        High_accuracy ans;
        ans.siz=siz;
        int res=0;
        for( int i=siz;i>=1;i-- )
        {
            res=res*10+num[i];
            ans.num[i]=res/b;
            res%=b;
        }
        while( ans.num[ans.siz] == 0 && ans.siz > 1 ) ans.siz--;
        return ans;
    }

    //高精除低精取余数(竖式模拟)
    int operator %( int b )
    {
        int res=0;
        for( int i=siz;i>=1;i-- )
        {
            res=res*10+num[i];
            res%=b;
        }
        return res;
    }
};