题解 | 元素方碑

import sys

t = int(sys.stdin.readline())
for _ in range(t):
    n, a = int(sys.stdin.readline()), list(map(int, sys.stdin.readline().split()))
    if sum(a) % n == 0:
        s = sum(a[i] for i in range(1, n, 2))
        print("YES" if s == sum(a) // n * (n // 2) else "NO")
    else:
        print("NO")