一些小东西

快读快读快读

1 inline int rd(){
2     int x=0,f=1; char ch=getchar();
3     while(!isdigit(ch)) {f=ch=='-'?0:1; ch=getchar();}
4     while(isdigit(ch))  {x=(x<<1)+(x<<3)+ch-'0'; ch=getchar();}
5     return f?x:-x;
6 }

快速幂

 1 ll ksm(ll a, ll b){
 2     if(b==1) return a;
 3     if(b==0) return 1;
 4     ll ans=1, base=a;
 5     while(b>0){
 6         if(b&1){
 7             ans*=base;
 8             ans%=mod;
 9         }
10         base*=base;
11         base%=mod;
12         b>>=1;
13     }
14     return ans;
15 }

 exgcd