70. Climbing Stairs

目录

• 题目描述
• 代码实现

题目描述

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?

代码实现

class Solution {
public:
    int climbStairs(int n) {
        if(n < 1)
            return 0;
        if(n == 1)
            return 1;
        if(n == 2)
            return 2;
        int first = 1;
        int second = 2;
        int result = 0;
        for(int i = 3;i <= n; i++){
            result = first + second;
            first = second;
            second =result;
        }
        return result;
        
    }
};