Climbing Stairs

You are climbing a stair case. It takes n steps to reach to the top.

Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top?

用递归到n = 44 时会超时根据菲波那切数列进行计算 n阶梯子爬法是n-1 和 n-2 阶梯子的总和

 1 int climbStairs(int n) {
 2     int a = 1;
 3     int b = 2;
 4     int i,c;
 5     if(1 == n)
 6         return 1;
 7     if(2 == n)
 8         return 2;
 9     for(i = 2; i < n; i++)
10     {
11         c = a + b;
12         a = b;
13         b = c;
14     }
15     return c;
16 }