题解 | 元素方碑

import sys

def solve():
    t = int(sys.stdin.readline())
    for _ in range(t):
        n = int(sys.stdin.readline())
        a = list(map(int, sys.stdin.readline().split()))
        total = sum(a)
        if total % n != 0:
            print("NO")
            continue
        target = total // n
        s_odd = 0
        for i in range(n):
            if i % 2 == 0:  
                s_odd += a[i]
        if n % 2 == 0:
            if s_odd == total // 2:
                print("YES")
            else:
                print("NO")
        else:
            expected_odd = ((n + 1) // 2) * target
            if s_odd == expected_odd:
                print("YES")
            else:
                print("NO")

solve()