求阶层

234.#include<iostream>
235.using namespace std;
236.int main()
237.{int fun(int);
238.int a,b,p,k,t;
239.cout<<"输入两个正整数:";
240.cin>>a>>b;
241.if(a<=0||b<=0)
242.{cout<<"输入错误,重新输入:";
245.cin>>a>>b;}
246.if(a<=b)
247.{t=a;
248.a=b;
249.b=t;}
250.k=a-b;
251.p=fun(a)/fun(b)*fun(k);
252.cout<<"p=m!/n!*(m-n)!="<<p<<endl;
253.return 0;
254.}
255.int fun(int n)
256.{int i,f=1;
257.for(i=1;i<=n;i++)
258.f=f*i;
259.return(f);
260.}