ZOJ 2829 Beautiful Number

Beautiful Number

Time Limit: 2 Seconds
Memory Limit: 65536 KB

Mike is very lucky, as he has two beautiful numbers, 3 and 5. But he is so greedy that he wants infinite beautiful numbers. So he declares that any positive number which is dividable by 3 or 5 is beautiful number. Given you an integer N (1 <= N <= 100000),
could you please tell mike the Nth beautiful number?

Input

The input consists of one or more test cases. For each test case, there is a single line containing an integer N.

Output

For each test case in the input, output the result on a line by itself.

Sample Input

1

2

3

4

Sample Output

3

5

6

9

这个题目的各种信息表示，输出是有规律而言的，

0 1 2 3 4 5 6 7

3 5 6 9 10 12 15

18 20 21 24 25 27 30

就是七个一循环，所以代码就很容易了：

#include<iostream>
#include<cstdio>
using namespace std;
int a[7]={3,5,6,9,10,12,15};
int main()
{
int n,m,p;
long long sum;
while(~scanf("%d",&n))
{
m=n/7;
p=n%7;
sum=a[p-1]+m*15;
printf("%lld\n",sum);
}
return 0;
}