题目链接:http://www.lydsy.com/JudgeOnline/problem.php?id=1968
水题,不要去想f(i)是怎么算出来的,考虑i对于答案的贡献,显然对于i的正整数倍都要+1,那么答案就是sigma(n/i)
贴代码:
#include<cstdio>
#include<cstring>
using namespace std;
int n;
long long ans;
int main(){
// freopen("1968.in","r",stdin);
// freopen("1968.out","w",stdout);
scanf("%d",&n);
ans=0;
for (int i=1;i<=n;i++) ans+=int(n/i);
printf("%d",ans);
return 0;
}
【写的有漏洞的,欢迎路过大神吐槽】
2016/12/24 23:19:08
Ending.