【快速乘】【乘】【乘！！！！】

快速乘可以做到a*b%m不爆long long,当a%m*b*m还会爆时，快速乘吧//蒟蒻被嘲笑了……

#include<cstdio>#include<cmath>#include<climits>#include<iostream>using namespace std;typedef short lld;int m=10;lld fx(lld x,lld y){if(y==0)return 0;if(y==1)return x%m;lld res;res=fx(x,y>>1);if((y&1)==1)return (res+res+x)%m;else return (res+res)%m;}int main(){short a=32767;short b=a*a;cout<<b<<endl;cout<<fx(a,a)<<endl;return 0;}