Dynamic Programming 02

There are n stairs, a person standing at the bottom wants to reach the top. The person can climb either 1 stair or 2 stairs at a time. Count the number of ways, the person can reach the top(order does matter)

Problem link :- click here

Code

import java.util.Scanner;

//	COUNT WAYS TO REACH THE N'TH STAIR

public class DynamicProgramming_02
{
	
	static int numberOfWaysToReachNthStair(int n, int arr[])
	{
		if(n==1)
		{
			arr[1] = 1;
			return 1;
		}
		if(n==2)
		{
			arr[2] = 2;
			return 2;
		}
		else
		{
			int ans = numberOfWaysToReachNthStair(n-1, arr) + numberOfWaysToReachNthStair(n-2, arr);
			arr[n] = ans;
			return ans;
		}
	}
	
	static int numberOfWaysToReachNthStair2(int n)
	{
		int arr[] = new int[n+1];
		
		arr[1] = 1;
		arr[2] = 2;
		
		for(int i=3; i<=n; i++)
			arr[i] = arr[i-1] + arr[i-2];
		
		return arr[n];
	}

	public static void main(String[] args)
	{
		Scanner s = new Scanner(System.in);
		
		System.out.print("Enter the number of stairs: ");
		int k = s.nextInt();
		
		int arr[] = new int[k+1];
		System.out.println(numberOfWaysToReachNthStair(k, arr));
		
		s.close();
	}

}