高精度模板

class Big{
    
    public:
        
        int size,num[2001];
        Big(){size=0;memset(num,0,sizeof num);}
        
        Big(int data){
            size=0;
            while(data!=0)
            {
                size++;
                num[size]=data%M;data/=M;
            }
        }
        
        inline void init(int data){
            size=0;
            while(data!=0)
            {
                size++;
                num[size]=data%M;data/=M;
            }
        }
        
        inline void copy(Big A){
            int s1=size,s2=A.size;
            size=s2;
            for(int i=s2;i>=1;i--) num[i]=A.num[i];
        }
};

inline int read()
{
    int x=0,f=1;char c=getchar();
    while(c>'9'||c<'0'){if(c=='-')f=-1;c=getchar();}
    while(c>='0'&&c<='9'){x=x*M+c-'0';c=getchar();}
    return x*f;
}

Big operator + (Big A,Big B)
{
    Big C;C.init(0);
    C.size=max(A.size,B.size);
    for(int i=1;i<=C.size;i++)
    {
        C.num[i]+=A.num[i]+B.num[i];
        C.num[i+1]+=C.num[i]/M,C.num[i]%=M;
    }
    if(C.num[C.size+1]!=0) C.size++;
    return C;
}

Big operator - (Big A,Big B)
{
    Big C;
    C.size=max(A.size,B.size);
    for(int i=1;i<=C.size;i++)
    {
        C.num[i]+=A.num[i]-B.num[i];
        if(C.num[i]<0) C.num[i+1]--,C.num[i]+=M;
    }
    while(!C.num[C.size]) C.size--;
    return C;
}

Big operator * (Big A,Big B)
{
    Big C;int s=A.size,s_=B.size;
    C.size=A.size+B.size;
    for(int i=1;i<=s;i++) for(int j=1;j<=s_;j++)
    {
        C.num[i+j-1]+=A.num[i]*B.num[j];
        if(C.num[i+j-1]>M) C.num[i+j]+=C.num[i+j-1]/M,C.num[i+j-1]%=M;
    }
    while(!C.num[C.size]) C.size--;
    return C;
}

Big operator /(Big A,int b)
{
    Big C;
    int s1=A.size,k;k=s1;
    for(int i=s1;i>=1;i--)
    {
        C.num[i]=A.num[i]/b;
        if(i!=1) A.num[i-1]+=(A.num[i]%b*10);
        A.num[i]/=b;
    }
    while(k>=1 && C.num[k]==0) k--;C.size=k;
    return C;
}

ostream & operator << (ostream &os,Big A)
{
    int s=A.size; os<<A.num[s];
    for(int i=s-1;i;i--) os<<setfill('0')<<setw(4)<<A.num[i];
    return os;
}


//说明
赋值: Big A;A.init(x);//x为int
Big A，B；A.copy(B);