快速乘模板

#include<iostream>#define ll unsigned long longusing namespace std;ll a,b,p;ll mult(ll t,ll k){ll f=0;for(;k;k>>=1,t=(t+t)%p)if(k&1)f=(f+t)%p;return f;}int main(){cin>>a>>b>>p;cout<<mult(a,b);return 0;}