代码请教

 1 #include<iostream>
 2 using namespace std;
 3 
 4 int fab(int n)
 5 {
 6     if (n == 1 || n == 2)
 7     {
 8         return 1;
 9     } else {
10         return fab(n - 2) + fab(n - 1);
11     }
12     
13 }
14 
15 int fab2 (int n)
16 {
17     int a[20];
18     a[1] = 1;
19     a[2] = 1;
20     for (int i = 3; i <= n; i++)
21     {
22         a[i] = a[i-2] + a[i-1];
23     }
24     return a[n];
25 }
26 
27 int main()
28 {    
29     for (int i = 1; i < 20; i++)
30     {
31         cout << fab (i) << endl;
32     }
33     cout << endl;
34     for (int i = 1; i < 20; i++)
35     {
36         cout << fab2 (i) << endl;
37     }
38     return 0;
39 }
40