【高精度】【模板】高精度模板

没有什么好说的，照着模板写就是了，稍微用了点手段，支持负数的减法了

  1 #include<cstdio>
  2 #include<cstring>
  3 #include<string>
  4 #include<algorithm>
  5 #include<vector>
  6 #include<iostream>
  7 using namespace std;
  8 const int maxn=510;
  9 struct bigint
 10 {
 11     int len,s[maxn];
 12     bigint()
 13     {
 14         len=1;
 15         memset(s,0,sizeof(s));
 16     }
 17     bigint(int num)
 18     {
 19         *this=num;
 20     }
 21     bigint(const char *num)
 22     {
 23         *this=num;
 24     }
 25     bigint operator = (int num)
 26     {
 27         char s[maxn];
 28         sprintf(s,"%d",num);
 29         *this=s;
 30         return *this;
 31     }
 32     bigint operator = (const char* num)
 33     {
 34         len=strlen(num);
 35         for(int i=0;i<len;i++) s[i]=num[len-i-1]-‘0‘;
 36         return *this;
 37     }
 38     string str() const
 39     {
 40         string res="";
 41         for(int i=0;i<len;i++) res=(char)(s[i]+‘0‘)+ res;
 42         if(res=="") res="0";
 43         return res;
 44     }
 45     void clean()
 46     {
 47         while(len>1 && !s[len-1])len--;
 48     }
 49     bigint operator + (const bigint &b)const
 50     {
 51         bigint c;
 52         c.len=0;
 53         for(int i=0,g=0;g||i<max(len,b.len);i++)
 54         {
 55             int x=g;
 56             if(i<len) x+=s[i];
 57             if(i<b.len) x+=b.s[i];
 58             c.s[c.len++]=x%10;
 59             g=x/10;
 60         }
 61         return c;
 62     }
 63     bool operator < (const bigint &b)const
 64     {
 65         if(len!=b.len) return len<b.len;
 66         for(int i=len-1;i>=0;i--)
 67         {
 68             if(s[i]!=b.s[i]) return s[i]<b.s[i];
 69         }
 70         return false;
 71     }
 72     bigint operator - (const bigint &b)
 73     {
 74         bigint c;c.len=0;
 75         for(int i=0,g=0;i<len;i++)
 76         {
 77             int x=s[i]-g;
 78             if(i<b.len) x-=b.s[i];
 79             if(x>=0) g=0;
 80             else
 81             {
 82                 g=1;
 83                 x+=10;
 84             }
 85             c.s[c.len++]=x;
 86         }
 87         c.clean();
 88         return c;
 89     }
 90     bigint operator * (const bigint &b)
 91     {
 92         bigint c;
 93         c.len=len+b.len;
 94         for(int i=0;i<len;i++)
 95         {
 96             for(int j=0;j<b.len;j++)
 97             {
 98                 c.s[i+j]+=s[i]*b.s[j];
 99             }
100         }
101         for(int i=0;i<c.len-1;i++)
102         {
103             c.s[i+1]+=c.s[i]/10;
104             c.s[i]%=10;
105         }
106         c.clean();
107         return c;
108     }
109 };
110 istream& operator >> (istream &in,bigint& x)
111 {
112     string s;
113     in>>s;
114     x=s.c_str();
115     return in;
116 }
117 ostream &operator << (ostream &out,const bigint &x)
118 {
119     out<<x.str();
120     return out;
121 }
122 int main()
123 {
124     bigint a,b;
125     cin>>a>>b;
126     if(a<b)
127     {
128         cout<<"-"<<b-a;
129     }
130     else
131     {
132         cout<<a-b;
133     }
134     return 0;
135 }