递归之斐波那契

斐波那契数列 f(0) = 0; f(1) = 1.......f(n) = f(n-1) + f(n - 2)
 1 unsigned Fibo(int n) {
 2     if (n == 0)
 3         return 0;
 4     if (n == 1)
 5         return 1;
 6     return Fibo(n - 1) + Fibo(n - 2);
 7 }
 8 unsigned Fibo_no_recursion(int n) {
 9     int a[200];//数组容量要大于n
10     a[0] = 0;
11     a[1] = 1;
12     for (int i = 2; i <= n; ++i) {
13         a[i] = a[i - 1] + a[i - 2];
14     }
15     return a[n];
16 }
17 unsigned Fibo_no_recursion2(int n) {
18     int a,b,result;
19     a = 0;
20     b = 1;
21     if (n == 0)
22         result = 0;
23     else if (n == 1)
24         result = 1;
25     else
26     for (int i = 2; i <= n; ++i) {
27         result = a + b;
28         a = b;
29         b = result;
30     }
31     return result;
32 }
33 int main() {
34     printf("%u
", Fibo_no_recursion(100));
35     printf("%u
", Fibo_no_recursion2(100));
36     printf("%u
", Fibo(38));//最慢，比两个非递归的慢的多的多的多
37     system("pause");
38     return 0;
39 }