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#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

dalao高精

标签：names   fill   false   als   let   space   this   char   clu   

原文地址：https://www.cnblogs.com/cwjr/p/13389504.html