题解 | 元素方碑

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int t=in.nextInt();
        while(t-- > 0){
            int n=in.nextInt();
            long[] a=new long[n+1];
            long sum=0;
            long evensum=0;
            for(int i=1;i<=n;i++){
                a[i]=in.nextLong();
                sum+=a[i];
                if(i%2==0){
                    evensum+=a[i];
                }
            }
        if(sum%n!=0){
            System.out.println("NO");
            continue;
        }
        long target=sum/n;
        int cnt=n/2;
        if(evensum==1L*cnt*target){
            System.out.println("YES");
        }else{
            System.out.println("NO");
        }
        }
    }
}