Pairs with specific difference .txt

import java.util.*;
import java.lang.*;
import java.io.*;
class GFG
 {
	 public static void main (String[] args) throws IOException
	 {
	 BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
	 StringBuffer sb=new StringBuffer();
	 int T=Integer.parseInt(br.readLine());
	 while(T-->0)
	 {
	     int n=Integer.parseInt(br.readLine());
	     String[] s=br.readLine().split("\\s");
	     int k=Integer.parseInt(br.readLine());
	     int[] arr=new int[n];
	     int[] dp=new int[n+1];
	     Arrays.fill(dp,-1);
	     for(int i=0;i<n;i++)
	     {
	         arr[i]=Integer.parseInt(s[i]);
	     }
	     Arrays.sort(arr);
	     sb.append(pairsum(arr,0,k,dp)+"\n");
	 }
	 System.out.print(sb);
	 }
	 public static int pairsum(int[] arr,int i,int k,int[] dp)
	 {
	     if(i+1>=arr.length)
	     {
	         return 0;
	     }
	     if(dp[i]!=-1)
	     {
	         return dp[i];
	     }
	     int smallans1=0,smallans2=0;
	     if(arr[i+1]-arr[i]<k)
	     {
	         smallans1=arr[i+1]+arr[i]+pairsum(arr,i+2,k,dp);
	     }
	     smallans2=pairsum(arr,i+1,k,dp);
	     return dp[i]=Math.max(smallans1,smallans2);
	 }
}