1000. 函数求值

class Solution {
public:
       int (int k, int n) {
             
       }
};

class Solution {
 public:
  int (int k, int n) {
    if (k == 0) {
      return n;
    } else if (k > 0) {
      int subsum = 0;
      for (int i = 1; i <= n; i++) {
        subsum += F(k - 1, i);
      }
      return subsum;
    } else {
      return -1;
    }
  }
};