递归计算多项式

#include <iostream>#include <stack>int power(int x, int n){if (n == 0)return 1;else{int res = 1;int base = x;while (n){if (n & 1)res *= base;base *= base;n >>= 1;}return res;}};int fn(int x, int n, int a[]){if (n == 0)return a[0];elsereturn fn(x, n - 1, a) + a[n] * power(x, n);};int main(int argc,char *argv[])  {  int a[3] = {1, 2, 4};int res = fn(2, 2, a);    return 0;  }