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)

unsigned Fibo(int n) {
    if (n == 0)
        return 0;
    if (n == 1)
        return 1;
    return Fibo(n - 1) + Fibo(n - 2);
}
unsigned Fibo_no_recursion(int n) {
    int a[200];//数组容量要大于n
    a[0] = 0;
    a[1] = 1;
    for (int i = 2; i <= n; ++i) {
        a[i] = a[i - 1] + a[i - 2];
    }
    return a[n];
}
unsigned Fibo_no_recursion2(int n) {
    int a,b,result;
    a = 0;
    b = 1;
    if (n == 0)
        result = 0;
    else if (n == 1)
        result = 1;
    else
    for (int i = 2; i <= n; ++i) {
        result = a + b;
        a = b;
        b = result;
    }
    return result;
}
int main() {
    printf("%u
", Fibo_no_recursion(100));
    printf("%u
", Fibo_no_recursion2(100));
    printf("%u
", Fibo(38));//最慢，比两个非递归的慢的多的多的多
    system("pause");
    return 0;
}