Bigint 重载了'='和‘+’和‘-’和‘×’和‘<<’和‘>>’

来源：互联网发布：科比巅峰数据编辑：程序博客网时间：2024/05/17 03:11
    #include<cstdio>           #include<iostream>           #include<vector>            #include<cstring>      #define LL long long           using namespace std;           struct bigint{               static const int base=1000000000;               static const int width=9;               vector<LL>s;               bigint (LL num=0){*this=num;}               bigint operator = (LL num){                   s.clear();                   do{                       s.push_back(num%base);                       num/=base;                   }while(num>0);                   return *this;               }               bigint operator = (const string& str){                   s.clear();                   int x,len=(str.length()-1)/width+1;                   for(int i=0;i<len;i++){                       int end=str.length()-i*width;                       int start=max(0,end-width);                       sscanf(str.substr(start,end-start).c_str(),"%d",&x);                       s.push_back(x);                   }                   return *this;               }               bigint operator + (const bigint& b) const{                   bigint c;                   c.s.clear();                   for(int i=0,g=0;;i++){                       if(g==0&&i>=s.size()&&i>=b.s.size())break;                       int x=g;                       if(i<s.size())x+=s[i];                       if(i<b.s.size())x+=b.s[i];                       c.s.push_back(x%base);                       g=x/base;                   }                   return c;               }               bigint operator - (const bigint& b) const{                   bigint c;                   c.s.clear();                   for(int i=0,g=0;;i++){                       if(g==0&&i>=s.size())break;                       int x=g;                       if(i<s.size())x+=s[i];                       if(i<b.s.size())x-=b.s[i];                       if(x<0)x+=base,g=-1;                       else g=0;                       c.s.push_back(x);                   }                   return c;               }            bigint operator * (const bigint& b) const{                bigint c;                c.s.clear();                LL i,j,g;                LL temp,temp1;                c.s.resize(s.size()+b.s.size());                for(i=0;i<s.size();i++){                    g=0,temp1=0;                    for(j=0;j<b.s.size();j++){                        LL x=c.s[i+j];                        temp=s[i]*b.s[j]+g;                        g=temp/base;                        x+=temp%base+temp1;                        temp1=x/base;                        x%=base;                        c.s[i+j]=x;                    }                    if(g!=0)                        c.s[i+j]=g;                }                if(temp1!=0)                    c.s[i+j]=temp1;                while(c.s.back()==0&&c.s.size()>1)                    c.s.pop_back();                return c;            }            bool operator < (const bigint&b) const{                   if(s.size()!=b.s.size())return s.size()<b.s.size();                   for(int i=s.size()-1;i>=0;i--)                       if(s[i]!=b.s[i])return s[i]<b.s[i];                   return false;               }               bool operator > (const bigint&b) const{return b<*this;}               bool operator <= (const bigint&b) const{return !(b<*this);}               bool operator >= (const bigint&b) const{return !(*this>b);}               bool operator != (const bigint&b) const{return b<*this|| *this<b;}               bool operator == (const bigint&b) const{return !(b<*this)&&!(*this<b);}          bigint operator *= (const bigint &b){*this=(*this)*b; return *this;}               bigint operator -= (const bigint &b){*this=(*this)-b; return *this;}            bigint operator += (const bigint &b){*this=(*this)+b; return *this;}             bigint operator ++ (int){*this=*this+1; return *this;}             bigint& operator ++ () {*this=*this+1; return *this;}            bigint operator -- (int){*this=*this-1; return *this;}             bigint& operator -- (){*this=*this-1; return *this;}             };           ostream& operator << (ostream &out,const bigint& x){               out<<x.s.back();               for(int i=x.s.size()-2;i>=0;i--){                   char buf[20];                   sprintf(buf,"%09d",x.s[i]);                   for(int j=0;j<strlen(buf);j++)out<<buf[j];                   }               return out;           }           istream& operator >> (istream &in,bigint&x){               string s;               if(!(in>>s))return in;               x=s;               return in;           }        int main(){            bigint a,b;            cin>>a>>b;            cout<<a*b;        }
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