力扣（LeetCode）试题70-爬楼梯 C++代码

方法：找着找着规律，发现是斐波那契数列，还是使用迭代的方法，驾轻就熟了，第一次一遍过

//找规律过程中，发现是斐波那契数列 f(n) = f(n-1) + f(n-2)

#include <iostream>

using namespace std;

class Solution 
{
public:
    int climbStairs(int n) 
    {
        if (n == 1) return 1;
        else if (n == 2) return 2;
        else
        {
            int pre_1 = 1;
            int pre_2 = 2;
            int cur;
            for (int k = 3; k <= n; k++)
            {
                cur = pre_1 + pre_2;
                pre_1 = pre_2;
                pre_2 = cur;
            }
            return cur;
        }
    }
};

int main()
{
    int n = 7;
    int result;
    Solution sol;
    result = sol.climbStairs(n);
    cout << result << endl;

    int u;
    cin >> u;
    return 0;
}