백준 - 2579 계단 오르기 (feat. java)

import java.util.Scanner;

public class Main {
	static int N;
	static int[] stairs;
	static int[] dp;
	
	public static void main(String[] args) {
		
		Scanner sc = new Scanner(System.in); 
		
		N = sc.nextInt();
		dp = new int[N+1];
		stairs = new int[N+1];
		
		for (int i = 1; i <= N; i++) {
			stairs[i] = sc.nextInt();
		}
		
		dp[1] = stairs[1];
		if (N >= 2) dp[2] = dp[1] + stairs[2];
		
		for (int i = 3; i <= N; i++) {
			dp[i] = Math.max(dp[i-2] + stairs[i], dp[i-3] + stairs[i-1] + stairs[i]);
		}
		
		System.out.println(dp[N]);
	}
}