第十二周 求数以二递减的阶乘（递归）

#include  <iostream>using namespace std;long  fac(int);int main(){    int n;    long x;    cout<<"输入需求的递归数值：";    cin>>n;    x=fac(n);    cout<<n<<"!="<<x<<endl;    return 0;}long fac(int n){    long m;    if(n==0)        m=0;    else if    (n<0)        cout<<"负数有错哦，给你个大嘴巴，啪！";    else if(n==1)        m=1;        else if(n==2)        m=2;    else        m=fac(n-2)*n;    return m;}

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