C++ 一些高精度算法

高精度乘法:

vector<int>mul(vector<int> a,int b)
{vector<int> c;
 int t = 0;
 for(int i = 0;i < a.size();i++)
 { t+=a[i]*b;
   c.push_back(t%10);
   t/=10;
 }
 while(t)
 {c.push_back(t%10);
  t/=10;
 }
 return c;
}

高精度除法:

vector<int>div(vector<int>a,int b)
{ vector<int>c;
  int t=0;
  bool is_first=true;
  int x =0;
  for(int i = a.size();i>=0;i--)
  {t=t*10+a[i];
   x=t/b;
   if(!is_first||x)
   { is_first=false;
     c.push_back(x);
   }
  t%=b;
  }
  reverse(c.begin(),c.end());
  return c;
}

两个高精度大数比较大小

vector<int>max_val(vector<int>a,vector<int>b)
{if(a.size()>b.size()) return a;
 if(a.size()<b.size()) return b;
 if(vector<int>(a.rbegin(),a.rend())>vector<int>(b.rbegin(),b.rend())) return a;
 return b;
}