模板 高精度大整数

#include<bits/stdc++.h>

#define clr(x,y) memset((x),(y),sizeof(x))

using namespace std;
typedef long long LL;

const int MaxL=400; //大数长度


//大整数
//减法只能大减小
struct bign
{
    int len, s[MaxL];

    //构造函数
    bign ()
    {
        memset(s, 0, sizeof(s));
        len = 1;
    }
    bign (int num) { *this = num; }
    bign (const char *num) { *this = num; }

    //*初始化
    void init(int num) //int初始化
    {
        *this=num;
    }
    void init(char *num) // 字符串初始化
    {
        *this=num;
    }
    void init(string num)
    {
        *this=num;
    }

    //去前导0
    void clean()
    {
        while(len>1 && !s[len-1]) len--;
    }

    //*赋值
    bign operator = (const bign &b)
    {
        clr(s,0);
        len=b.len;
        for (int i=0;i<len;++i)
            s[i]=b.s[i];

        return *this;
    }
    bign operator = (const int num)
    {
        char s[MaxL];
        sprintf(s,"%d",num);
        *this = s;
        return *this;
    }
    bign operator = (const char *num)
    {
        while (num[0]==‘0‘) ++num;  //去前导0

        clr(s,0);
        len = strlen(num);
        for(int i=0;i<len;i++) s[i] = num[len-i-1]-‘0‘;
        return *this;
    }
    bign operator = (string num)
    {
        *this=num.c_str();
        return *this;
    }

    //大整数四则运算
    //加法
    bign operator + (const bign &b) const //+
    {
        bign c;
        c.len=0;
        for(int i=0, g=0; g || i<max(len,b.len); i++)
        {
            int x=g;
            if(i<len) x+=s[i];
            if(i<b.len) x+=b.s[i];
            c.s[c.len++]=x%10;
            g=x/10;
        }
        return c;
    }
    bign operator + (const int &b) const
    {
        bign c;
        c.init(b);
        return *this+c;
    }

    //乘法
    bign operator * (const bign &b) //*
    {
        bign c;
        c.len=len+b.len;
        for(int i=0;i < len;i++)
        {
            for(int j=0; j<b.len; j++)
            {
                c.s[i+j]+=s[i]*b.s[j];
            }
        }
        for(int i=0; i<c.len;i++)
        {
            c.s[i+1]+=c.s[i]/10;
            c.s[i]%=10;
        }
        c.clean();
        return c;
    }
    bign operator * (const int &b)
    {
        bign c;
        c.init(b);
        return (*this)*c;
    }

    //减法
    bign operator - (const bign &b)
    {
        bign c;
        c.len=0;
        for(int i=0,g=0;i<len;i++)
        {
            int x=s[i]-g;
            if(i<b.len) x-=b.s[i];
            if(x>=0) g=0;
            else
            {
                g=1;
                x+=10;
            }
            c.s[c.len++]=x;
        }
        c.clean();
        return c;
    }
    bign operator - (const int &b)
    {
        bign c;
        c.init(b);
        return *this-c;
    }

    //除法
    bign operator / (const bign &b)
    {
        bign c,f;
        for(int i=len-1;i>=0;i--)
        {
            f=f*10;
            f.s[0]=s[i];
            while(f >= b)
            {
                f=f-b;
                c.s[i]++;
            }
        }
        c.len=len;
        c.clean();
        return c;
    }
    bign operator / (const int &b)
    {
        bign c;
        c.init(b);
        return (*this)/c;
    }

    //取余
    bign operator % (const bign &b)
    {
        bign r=*this / b;
        r=*this-r*b;
        return r;
    }
    bign operator % (const int &b)
    {
        bign c;
        c.init(b);
        return (*this)%c;
    }


    //大小比较
    //大于号
    bool operator < (const bign &b)
    {
        if(len!=b.len) return len<b.len;
        for(int i=len-1;i>=0;i--)
        {
            if(s[i]!=b.s[i]) return s[i]<b.s[i];
        }
        return false;
    }
    bool operator < (const int &b)
    {
        bign c;
        c.init(b);
        return *this<c;
    }

    //小于号
    bool operator > (const bign &b)
    {
        if(len!=b.len) return len>b.len;
        for(int i=len-1;i>=0;i--)
        {
            if(s[i]!=b.s[i]) return s[i]>b.s[i];
        }
        return false;
    }
    bool operator > (const int &b)
    {
        bign c;
        c.init(b);
        return *this>c;
    }

    //等于号
    bool operator == (const bign &b)
    {
        if (len!=b.len) return false;
        for (int i=len-1;i>=0;--i)
            if (s[i]!=b.s[i]) return false;

        return true;
    }
    bool operator == (const int &b)
    {
        bign c;
        c.init(b);
        return *this==c;
    }

    bool operator != (const bign &b)
    {
        return !(*this == b);
    }
    bool operator != (const int &b)
    {
        bign c;
        c.init(b);
        return *this!=c;
    }

    bool operator <= (const bign &b)
    {
        return *this<b || *this== b;
    }
    bool operator <= (const int &b)
    {
        bign c;
        c.init(b);
        return *this<c || *this==c;
    }

    bool operator >= (const bign &b)
    {
        return *this>b || *this==b;
    }
    bool operator >= (const int &b)
    {
        bign c;
        c.init(b);
        return *this>c || *this==b;
    }

    //转化为字符串
    string str() const
    {
        string res = "";
        for(int i=0;i<len;i++) res=char(s[i]+‘0‘)+res;
        return res;
    }

    //转化为LL
    LL Integer() const
    {
        LL res=0;
        for (int i=len-1;i>=0;--i)
        {
            res=(10*res+s[i]);
        }
        return res;
    }
};

istream& operator >> (istream &in, bign &x)
{
    string s;
    in >> s;
    x = s.c_str();
    return in;
}

ostream& operator << (ostream &out, const bign &x)
{
    out << x.str();
    return out;
}

//大整数取模
bign Sqrt(bign x)
{
    bign remain=0;
    bign odd=0;
    bign ans=0;

    int group=0,k=0;

    string s=x.str();
    int len=s.length();

    if (len%2==1)
    {
        group=s[0]-‘0‘;
        k=-1;
    }
    else
    {
        group=(s[0]-‘0‘)*10+s[1]-‘0‘;
        k=0;
    }

    for (int j=0;j<(len+1)/2;++j)
    {
        if (j!=0) group=((s[2*j+k]-‘0‘)*10+(s[2*j+k+1]-‘0‘));

        odd=ans*20+1;
        remain=remain*100+group;

        int cnt=0;
        while (remain>=odd)
        {
            ++cnt;
            remain=remain-odd;
            odd=odd+2;
        }
        ans=ans*10+cnt;

    }

    return ans;
}

int main(void)
{
    #ifdef ex
    //freopen ("../in.txt","r",stdin);
    //freopen ("../out.txt","w",stdout);
    #endif
}