#include <iostream>
using namespace std ;
double chance(unsigned all ,unsigned choice) ; //计算几率的函数
int main()
{
double fieldnumber = chance(47,5) ;
double specialnumber = chance(27,1) ;
cout<<"中头奖的几率为:"<<fieldnumber * specialnumber <<endl;
return 0;
}
double chance(unsigned all ,unsigned choice)
{
double result = 1.0 ;
unsigned a =all ;
double c = choice ; //要使用除法(/)所以分子让它转化成浮点数不被截断
for( ;c>0 ;a--,c--)
{
result *= c/a ;
}
return result ;
}