[백준] 2579번 : 계단 오르기 - Java(자바)

https://www.acmicpc.net/problem/2579

import java.util.*;
public class Main {
    public static void main(String args[]) {
        Scanner s=new Scanner(System.in);
        int n=s.nextInt();
        int arr[]=new int[n+1];
        int num[]=new int[n+1];
        for(int i=1;i<=n;i++) arr[i]=s.nextInt();
        num[1]=arr[1];
        if(n>1) num[2]=arr[1]+arr[2];
        for(int i=3;i<=n;i++){
            num[i]=Math.max(num[i-2],num[i-3]+arr[i-1])+arr[i];
        }
        System.out.print(num[n]);
    }
}