取模优化

#include <iostream>
#include <stdio.h>
#include <string.h>
#include <algorithm>
using namespace std ; 
long long multi(long long x , long long y , long long mod ) {
	long long tmp = (x * y - (long long)((long double)x / mod * y + 0.5 ) * mod) ;
	return tmp < 0 ? tmp + mod : tmp ;
}
int main () {
	int a , b ;
	cin >> a >> b ;
	cout << multi(a,1,b) ;
	return 0 ;	
}

只是一个存档