HDU 4349 Xiao Ming's Hope 找规律

原题链接：http://acm.hdu.edu.cn/showproblem.php?pid=4349

Xiao Ming's Hope

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 1723    Accepted Submission(s): 1144

Problem Description

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?

 

Input

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

 

Output

A single line with the number of odd numbers of C_(n,0),C_(n,1),C_(n,2)...C_(n,n).

 

Sample Input

1
2
11

 

Sample Output

2
2
8

 

Author

HIT

 

Source

2012 Multi-University Training Contest 5

 

Recommend

zhuyuanchen520

题意

给你个n，问你第n行的二项式系数中有多少个奇数项。

题解

就打打表找规律，发现答案就是n的二进制中1的个数的二的幂。

代码

#include<cstdio>
#include<bitset>
int n;
int main(){
    while(scanf("%d",&n)==){
        std::bitset<> bi(n);
        printf("%d\n",<<(bi.count()));
    }
    return ;
}