常用工具整理

1. 宏定义

   #define ll long long
   #define db double
   #define rep(i,j,k) for(int i = (j), i <= (k), i++)
   #define Rrep(i,j,k) for(int i = (j), i >= (k), i--)
   #define file(s)     freopen(#s".in","r",stdin), freopen(#s".out","w",stdout)
   const int inf = 0x3f3f3f3f;

2. 模板函数

   template<class T> inline T gcd(T a, T b) { return b == 0 ? a : gcd(b, a % b); }
   template<class T> inline void read(T& ans){
       int f = 1; char c = getchar(); ans=0;
       while(c < '0' || c > '9')
           if(c == '-') f = -1, c = getchar();
       while('0' <= c && c <= '9')
           ans = (ans << 1) + (ans << 3) + (c ^ 48), c = getchar();
       ans = ans * f;
   }