高精度模板（修改中）

  1 #include<iostream>
  2 #include<algorithm>
  3 #include<cstdio>
  4 #include<cstdlib>
  5 #include<cmath>
  6 #include<cstring>
  7 #include<vector>
  8 #define xh(a,b,c)for(int a=(b);a<=(c);a++)
  9 #define dxh(a,b,c)for(int a=(b);a>=(c);a--)
 10 #define bxh(a,b)for(int a=beg[b];a;a=ne[a])
 11 #define hy(a)memset(a,0,sizeof(a))
 12 #define sqr(a) (a)*(a)
 13 #define Max(a,b) a=max(a,b)
 14 #define Min(a,b) a=min(a,b)
 15 #define ll long long
 16 #define lof double
 17 #define ch char
 18 using namespace std;
 19 void qin(int &x){
 20     int base=1,num;
 21     ch c=getchar();
 22     while(!(c==‘-‘||c>=‘0‘&&c<=‘9‘||c==EOF))c=getchar();
 23     if(c==EOF)exit(0);
 24     if(c==‘-‘)base=-1,c=getchar();
 25     num=c-‘0‘;
 26     c=getchar();
 27     while(c>=‘0‘&&c<=‘9‘){
 28         num*=10;
 29         num+=c-‘0‘;
 30         c=getchar();
 31     }
 32     x=num*base;
 33 }
 34 ch integ[50];
 35 void qout(int x){
 36     if(x<0)putchar(‘-‘),x=-x;
 37     int len=0;
 38     do{
 39         integ[len++]=x%10+‘0‘;
 40         x/=10;
 41     }while(x);
 42 
 43     while(len--){
 44         putchar(integ[len]);
 45     }
 46 }
 47 struct bigint{
 48         vector<int> v;
 49         bigint(long long a = 0){
 50             *this = a;
 51         }
 52         bigint operator =(long long a){
 53             v.clear();
 54             while(a){
 55                 v.push_back(a%10000);
 56                 a/=10000;
 57             }
 58             return *this;
 59         }
 60         bigint operator =(string a){
 61             v.clear();
 62             int x,len=(a.length()-1)/4+1;
 63             xh(i,0,len-1){
 64                 int e,s;
 65                 e=a.length()-i*4;
 66                 s=max(0,e-4);
 67                 sscanf(a.substr(s,e-s).c_str(),"%d",&x);
 68                 v.push_back(x);
 69             }
 70             return *this;
 71         }
 72         bigint operator +(bigint &b){
 73             bigint c;
 74             c.v.clear();
 75             for(int i=0,g=0;;i++){
 76                 if(g==0&&i>=v.size()&&i>=b.v.size())break;
 77                 int x=g;
 78                 if(i<v.size())x+=v[i];
 79                 if(i<b.v.size())x+=b.v[i];
 80                 c.v.push_back(x%10000);
 81                 g=x/10000;
 82             }
 83             return c;
 84         }
 85         bigint operator *(bigint &b){
 86             bigint c;
 87             c.v.clear();
 88             c.v.resize(v.size()+b.v.size());
 89             for(int i=0;i<v.size();i++)
 90                 for(int j=0;j<b.v.size();j++){
 91                     c.v[i+j]+=b.v[j]*v[i];
 92                     c.v[i+j+1]+=c.v[i+j]/10000;
 93                     c.v[i+j]%=10000;
 94                 }
 95             if(c.v[c.v.size()-1]==0)c.v.pop_back();
 96             return c;
 97         }
 98     
 99     
100 };
101 ostream& operator<< (ostream &out,const bigint &x){
102     out<<x.v.back();
103     dxh(i,x.v.size()-2,0){
104         char s[10];
105         sprintf(s,"%04d",x.v[i]);
106         xh(j,0,strlen(s)-1)cout<<s[j];
107     }
108     return out;
109 }
110 istream& operator >>(istream &in,bigint &x){
111     string s;
112     if(!(in>>s))return in;
113     x=s;
114 }
115 bigint a,b,c;
116 int main(){
117     cin>>a;
118     cin>>b;
119     c=a*b;
120     cout<<c<<endl;
121     return 0;
122 }