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

계단 오르기.java

import java.util.*;

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