Climbing Stairs - LeetCode 70

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

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

 

Example 1:

Input: n = 2
Output: 2
Explanation: There are two ways to climb to the top.
1. 1 step + 1 step
2. 2 steps

Example 2:

Input: n = 3
Output: 3
Explanation: There are three ways to climb to the top.
1. 1 step + 1 step + 1 step
2. 1 step + 2 steps
3. 2 steps + 1 step

 

Solution(Only function):

class Solution {

    public int climbStairs(int n) {

        

         

        if(n==1)

            return 1;

        else if(n==2)

            return 2;

        else{

            int x=1,y=2;

            

            int index=3,sum=0;

            

            while(index<=n) {

                sum=x+y;

                x=y;

                y=sum;

                index++;

            }

            return sum;

        }   

    }

}