Description
There is sequence 1, 12, 123, 1234, ..., 12345678910, ... . Given first N elements of that sequence. You must determine amount of numbers in it that are divisible by 3.
Input
Input contains N (1<=N<=231 - 1).
Output
Write answer to the output.
Sample Input
4
Sample Output
2
#include<iostream>
#include<cstdio>
using namespace std;
int main()
{
int n;
while(scanf("%d",&n)!=EOF)
{
int ans=(n/3)*2+((n%3)==2?1:0);
printf("%d\n",ans);
}
return 0;
}
原文：http://www.cnblogs.com/a972290869/p/4235805.html