蓝桥杯 结点选择只有70分

为什么蓝桥杯 结点选择只有70分
我用的python
是从网上抄的代码

def dfs(now,pre):
    global value,table
    # print('now',now)
    # print('pre',pre)
    for i in table.get(now):
        if i !=pre:
            dfs(i,now)
            # print('dfs完成！',now,i)
            value[now][0]+=max(value[i][0],value[i][1])
            value[now][1]+=value[i][0]
            # print(value[now][0],value[now][1])

n = int(input())
value = list(map(int, input().split()))
value = list(map(lambda x:[0,x],value))
value.insert(0,0)
# print(value)
table = {}
for i in range(n):
    table.update({i + 1: []})
for i in range(n - 1):
    father, child = list(map(int, input().split()))
    table.get(father).append(child)
    table.get(child).append(father)
# print(table)
dfs(3, 0)
print(max(value[3][0], value[3][1]))

你看看这行不行

def dfs(tree, pre, f):
    value = 0
    for child in tree[pre]:
        value1 = dfs(tree, child, False)
        if not f:
            value2 = dfs(tree, child, True) + child
            if value2 > value1:
                value1 = value2
        value += value1
    return value
    
    
n = int(input())
value = list(map(int, input().split()))
tree = {}
sroot = [i for i in range(1,n+1)]
for i in range(n + 1):
    tree.update({i: []})
for i in range(n - 1):
    father, child = list(map(int, input().split()))
    tree.get(father).append(child)
    if child in sroot:
        sroot.remove(child)
tree[0] = sroot
print(dfs(tree, 0, False))