/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
 
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		// -1,0,3,5,9,12
		int arr[]={2,4,6,7,8};
		int res = maximumSubsetExcludingAdjacent(arr);	
		System.out.println(res);
	}
 
	public static int maximumSubsetExcludingAdjacent(int[] arr){
 
		int []dp =new int[arr.length];
		dp[0]=arr[0];
		dp[1]=Math.max(dp[0],arr[1]);
		for(int i=2;i<arr.length; i++){
			dp[i] = Math.max(dp[i-1],arr[i]+dp[i-2]);
		}
 
		return dp[arr.length-1];
 
	}
}

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