Help me in solving ADJSUMPAR problem

help
,
1

My issue

can you explain this logic breffly

My code

import java.util.*;
import java.lang.*;
import java.io.*;

class Codechef
{
    public static void main(String[] args) throws java.lang.Exception
    {
        Scanner sc = new Scanner(System.in);
        int t = sc.nextInt();
        while (t-- > 0) {
            int n = sc.nextInt();
            int[] b = new int[n];
            for (int i = 0; i < n; i++)
                b[i] = sc.nextInt();
            int count = 0;
            if (n % 2 == 1) {
                System.out.println("NO");
            } else {
                for (int i = 0; i < n; i++) {
                    if (b[i] == 1)
                        count++;
                }
                if (count % 2 == 0)
                    System.out.println("YES");
                else
                    System.out.println("NO");
            }


        }
    }
}

Learning course: Roadmap to 3*
Problem Link: https://www.codechef.com/learn/course/klu-roadmap-3star/KLURMP300A/problems/ADJSUMPAR