VtcEX1 - Online Java Compiler & Debugging Tool

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        int n = scanner.nextInt();
        int[] a = new int[n + 1]; // 1-based indexing

        // Input using for loop
        for (int i = 1; i <= n; i++) {
            a[i] = scanner.nextInt();
        }
		if(n==1){
			System.out.println(Math.max(a[1],0));
			return;
		}

        int[] dp = new int[n + 1];
        dp[1] = Math.max(a[1], 0);
        dp[2] = Math.max(a[1], Math.max(a[2], 0));

        //general formula
        for (int i = 3; i <= n; i++) {
            dp[i] = Math.max(dp[i - 1], a[i] + dp[i - 2]);
        }

        System.out.println(dp[n]);
    }
}