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應該說是一個純數學的題目，考察錯排的概率。
 #include <stdio.h>
#define DEBUG 1
int main()
   {
 #if DEBUG
freopen("C:\\Documents and Settings\\Administrator\\桌面\\in.in","r",stdin) ;
freopen("C:\\Documents and Settings\\Administrator\\桌面\\out.out","w",stdout) ;
#endif
__int64 i, n, sets, s, fenmu ;
double p, temp ;
scanf("%I64d", &sets ) ;
  while( sets-- ){
scanf("%I64d", &n ) ;
p = 1 ;
s = 1 ;
fenmu = 1 ;
for( i=1; i<=n; ++i ){
s *= -1 ;
fenmu *= i ;
p += s/(double)fenmu ;
 }
printf("%.2lf%%\n", 100*p ) ;
}
 }
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