[恢]hdu 1465

2011-12-16 02:01:14

地址：http://acm.hdu.edu.cn/showproblem.php?pid=1465

题意：中文。。

mark：错拍问题。。。递推。dp[i] = (i-1) * (dp[i-1] + dp[i-2])

代码：

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


long long dp[25] = {0, 0, 1} ;
int main ()
{
    int i ;
    for(i = 3 ; i <= 20 ; i++)
        dp[i] = (i-1)*(dp[i-1]+dp[i-2]) ;
    while (~scanf ("%d", &i))
        printf ("%I64d\n", dp[i]) ;
    return 0 ;
}