백준 2579번(Java)

import java.io.*;

public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		int n = Integer.parseInt(br.readLine());
		
		int[] dp = new int[n+1];
		int[] arr = new int[n+1];
		
		for(int i=1; i<=n; i++) {
			arr[i] = Integer.parseInt(br.readLine());
		}
		
		dp[1] = arr[1];
		
		if(n>=2) {
			dp[2] = arr[1]+arr[2];
		}
		
		for(int i=3; i<=n; i++) {
			dp[i] = Math.max(dp[i-2], dp[i-3]+arr[i-1]) + arr[i];
		}
		
		System.out.println(dp[n]);
	}
}