首页 > ACM题库 > HDU-杭电 > HDU 4349-Xiao Ming’s Hope-数学相关-[解题报告]HOJ
2015
05-23

HDU 4349-Xiao Ming’s Hope-数学相关-[解题报告]HOJ

Xiao Ming’s Hope

问题描述 :

Xiao Ming likes counting numbers very much, especially he is fond of counting odd numbers. Maybe he thinks it is the best way to show he is alone without a girl friend. The day 2011.11.11 comes. Seeing classmates walking with their girl friends, he coundn’t help running into his classroom, and then opened his maths book preparing to count odd numbers. He looked at his book, then he found a question "C(n,0)+C(n,1)+C(n,2)+…+C(n,n)=?". Of course, Xiao Ming knew the answer, but he didn’t care about that , What he wanted to know was that how many odd numbers there were? Then he began to count odd numbers. When n is equal to 1, C(1,0)=C(1,1)=1, there are 2 odd numbers. When n is equal to 2, C(2,0)=C(2,2)=1, there are 2 odd numbers…… Suddenly, he found a girl was watching him counting odd numbers. In order to show his gifts on maths, he wrote several big numbers what n would be equal to, but he found it was impossible to finished his tasks, then he sent a piece of information to you, and wanted you a excellent programmer to help him, he really didn’t want to let her down. Can you help him?

输入:

Each line contains a integer n(1<=n<=108)

输出:

Each line contains a integer n(1<=n<=108)

样例输入:

1
2
11

样例输出:

2
2
8

/*
分析:
    找规律 or lucas定理。
    看这里看这里:http://blog.csdn.net/julyana_lin/article/details/7840491。。。

    24K纯数学盲暴力打表找规律的。。

                                                2013-07-17
*/

#include"iostream"
#include"cstdio"
#include"cstring"
using namespace std;
int main()
{
	int n;
	int i;
	int cnt,ans;
	while(scanf("%d",&n)!=-1)
	{
		cnt=0;
		ans=1;
		while(n)	{cnt+=n%2;n/=2;}
		for(i=0;i<cnt;i++)	ans*=2;
		printf("%d\n",ans);
	}
	return 0;
}

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参考:http://blog.csdn.net/ice_crazy/article/details/9359025