力扣（LeetCode）试题70-爬楼梯 C++代码

 1 //找规律过程中，发现是斐波那契数列 f(n) = f(n-1) + f(n-2)
 2 
 3 #include <iostream>
 4 
 5 using namespace std;
 6 
 7 class Solution 
 8 {
 9 public:
10     int climbStairs(int n) 
11     {
12         if (n == 1) return 1;
13         else if (n == 2) return 2;
14         else
15         {
16             int pre_1 = 1;
17             int pre_2 = 2;
18             int cur;
19             for (int k = 3; k <= n; k++)
20             {
21                 cur = pre_1 + pre_2;
22                 pre_1 = pre_2;
23                 pre_2 = cur;
24             }
25             return cur;
26         }
27     }
28 };
29 
30 int main()
31 {
32     int n = 7;
33     int result;
34     Solution sol;
35     result = sol.climbStairs(n);
36     cout << result << endl;
37 
38     int u;
39     cin >> u;
40     return 0;
41 }