题解 | 元素方碑

import sys

N = int(input())
for i in range(N):
    length = int(input())
    arr = list(map(int, input().split(' ')))
    if(length==1|length==2):
        print('YES')
        continue
    else:
        sums = sum(arr)
        ave = sums/length
        if (sums%length!=0):
            print('NO')
            continue
        else:
            for j in range(1, length-1):
                arr[j+1] += arr[j-1] - ave
                arr[j-1] = ave
            if(arr[length-1]==ave):
                print('YES')
                continue
            else:
                print('NO')
                continue