C实例 数列

#include <stdio.h>



int factorial(int n) {

   int f;



   for(f = 1; n > 1; n--)

      f *= n;



   return f;

}



int npr(int n,int r) {

   return factorial(n)/factorial(n-r);

}



int main() {

   int n, r;



   n = 4;

   r = 3;



   printf("%dp%d = %d \n", n, r, npr(n,r));



   return 0;

}