利用遞歸算法編程實現：N！+2N (N從鍵盤輸入)

main()

{double fac(unsigned n);

double pow(unsigned n);

unsigned n;

double f,p,sum;

printf("input n= ");

scanf("%d",&n);

f=fac(n);

p=pow(n);

sum=f+p;

printf("sum=%.0f ",sum);

}

double fac(unsigned n)

{double f;

if(n==1||n==0)f=1;

if(n>1)f=fac(n-1)*n;

return(f);

}

double pow(unsigned n)

{double p;

if(n==0)p=1;

if(n>0)p=pow(n-1)*2;

return(p);

}