第三章第三十题杨辉三角求某行某列的数

#include<stdio.h>

int main()

{

 double fun(double m,double n,double S1,double S2);

 double m,n,S1,S2;char ch;

 do

 {

     printf("请输入行号和列号：");

     scanf("%lf%lf",&m,&n);

     S1=m-1;

        S2=m-n;

     printf("第%.0lf行第%.0lf列的数是：%.0lf\n",m,n,fun(m,n,S1,S2));

  printf("是否继续？[y/n][y]");

  while((ch=getchar())!='\n');

 }while((ch=getchar())=='y'||ch=='\n');

 return 0;

}

double fun(double m,double n,double S1,double S2)

{

 double i;

 for(i=m-2;i>=1;i--)

  S1=S1*i;

 for(i=m-n-1;i>=1;i--)

  S2=S2*i;

 return S1/S2;

}