[恢]hdu 2048

2011-12-16 02:05:33

地址：http://acm.hdu.edu.cn/showproblem.php?pid=2048

题意：中文。

mark：算错拍概率。7以上不变了- -。。。

代码：

# include <stdio.h>
# include <string.h>


long long dp[25] = {0, 0, 1} ;
long long factorial[25] = {1, 1, 2} ;


int main ()
{
    int i ;
    for(i = 3 ; i <= 20 ; i++)
    {
        dp[i] = (i-1)*(dp[i-1]+dp[i-2]) ;
        factorial[i] = factorial[i-1]*i ;
    }
    scanf ("%d", &i) ;
    while (~scanf ("%d", &i))
        printf ("%.2lf%%\n", 1.0*dp[i] / factorial[i] * 100.0) ;
    return 0 ;
}