dalao高精

(from zyf)

#ifndef MY_BIGN_H
#define MY_BIGN_H 1
#pragma GCC system_header
#include<cstring>
#include<algorithm>
#include<iostream>
using std::max;
using std::istream;
using std::ostream;
using std::string;

namespace zyf {
	struct bign {
		static const int maxlen=5000,limit=10000,width=4;
		int len,bit[maxlen];
		int& operator[](int p) {
			return bit[p];
		}
		void ClearBit() {
			memset(bit,0,sizeof(bit));
		}
		void Delete0() {
			for(; !bit[len-1] && len>1; --len);
		}

		bign(int p=0) {
			*this=p;
		}
		bign& operator=(int p) {
			ClearBit();
			len=p?0:1;
			for(; p; p/=limit) bit[len++]=p%limit;
			return *this;
		}
		bign(const char *p) {
			*this=p;
		}
		bign& operator=(const char *p) {
			ClearBit();
			len=0;
			for(int i=strlen(p)-1; i>=0; i-=4) {
				int now=0;
				for(int j=max(0,i-width+1); j<=i; ++j) now=now*10+(p[j]-'0');
				bit[len++]=now;
			}
			return *this;
		}

		bign& operator+=(bign b) {
			len=max(len,b.len)+1;
			for(int i=0; i<len; ++i) bit[i]+=b[i],bit[i+1]+=bit[i]/limit,bit[i]%=limit;
			Delete0();
			return *this;
		}
		bign& operator-=(bign b) {
			for(int i=0; i<len; ++i) {
				bit[i]-=b[i];
				if(bit[i]<0) bit[i]+=limit,--bit[i+1];
			}
			Delete0();
			return *this;
		}
		bign& operator*=(bign b) {
			bign a=*this;
			ClearBit();
			len=a.len+b.len;
			for(int i=0; i<a.len; ++i)
				for(int j=0; j<b.len; ++j)
					bit[i+j]+=a[i]*b[j],bit[i+j+1]+=bit[i+j]/limit,bit[i+j]%=limit;
			Delete0();
			return *this;
		}
		bign& operator/=(int b) {
			for(int i=len-1; i>0; --i) bit[i-1]+=limit*(bit[i]%b),bit[i]/=b;
			bit[0]/=b;
			Delete0();
			return *this;
		}

		bool operator<(bign b) const {
			if(len>b.len) return false;
			if(len<b.len) return true;
			for(int i=len-1; i>=0; --i)
				if(bit[i]!=b[i]) return bit[i]<b[i];
			return bit[0]<b[0];
		}
		bool operator==(bign b) const {
			return !(*this<b) && !(b<*this);
		}
		bool operator!=(bign b) const {
			return !(*this==b);
		}
		bool operator>(bign b) const {
			return !(*this<b) && !(*this==b);
		}
		bool operator<=(bign b) const {
			return *this<b || *this==b;
		}
		bool operator>=(bign b) const {
			return *this>b || *this==b;
		}

		bool odd() {
			return bit[0]%2==1;
		}
		bool even() {
			return bit[0]%2==0;
		}
	};
	bign operator+(bign a,bign b) {
		return a+=b;
	}
	bign operator-(bign a,bign b) {
		return a-=b;
	}
	bign operator*(bign a,bign b) {
		return a*=b;
	}
	bign operator/(bign a,int b) {
		return a/=b;
	}
	istream& operator>>(istream &is,bign &p) {
		string s;
		is>>s;
		p=s.c_str();
		return is;
	}
	ostream& operator<<(ostream &os,bign p) {
		os.fill('0');
		os<<p.bit[p.len-1];
		for(int i=p.len-2; i>=0; --i) {
			os.width(bign::width);
			os<<p.bit[i];
		}
		return os;
	}

	bign sqrt(bign x) {
		bign head=1,tail=x;
		while(head<=tail) {
			bign mid=(head+tail)/2;
			if(x<mid*mid) tail=mid-1;
			else head=mid+1;
		}
		return tail;
	}
}
using zyf::bign;
#endif