2015年NEUACM一月月赛 J: Eliminate zero AC

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问题 J: Eliminate zero AC

时间限制: 1 Sec 内存限制: 128 MB

题目描述

Last night,Kid submitted a problem for many times but he got many WA,so he is sad.Out of

sympathy, his coach gave him a very simple problem so that Kid can solve it quickly. The problem

is to select as many numbers as possible range 1 to n so that among these selected number there

are no number can be divided exactly by other number. Can you solve it as quick as Kid?

输入

There are multiple cases.

For each case, there is a integer n(1<=n<=10^9)

输出

For each case,just output the answer.(the most numbers you can select)

样例输入

样例输出

提示

You can select {2,3,5} or {3,4,5}... but you can’t select {2,3,4,5} because 2|4.

So the answer is 3.

题解：有规律。详见代码。

 1 #include <stdio.h>
 2  
 3 int main()
 4 {
 5 #ifdef CDZSC_OFFLINE
 6     freopen("in.txt", "r", stdin);
 7     freopen("out.txt", "w", stdout);
 8 #endif
 9     int n;
10     while(~scanf("%d", &n))
11     {
12         if(n % 2)
13             printf("%d\n", (n >> 1) + 1);
14         else
15             printf("%d\n", n >> 1);
16     }
17     return 0;
18 }

View Code

2015年NEUACM一月月赛 J: Eliminate zero AC

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原文地址：http://www.cnblogs.com/LiuACG/p/4264443.html