Laskettelukeskus

from collections import defaultdict
import sys
input = sys.stdin.readline

def dfs(node, graph, counts, visited):
    # please python
    sys.setrecursionlimit(200000)

    
    visited[node] = True
    plows = 0
    
    for child in graph[node]:
        if not visited[child]:
            plows_for_child = dfs(child, graph, counts, visited)
            counts[node - 1] -= plows_for_child
            plows += plows_for_child
    
    if counts[node - 1] > 0:
        plows += counts[node-1]
        counts[node - 1] = 0

    return plows

n = int(input())
paths = [tuple(map(int, input().split())) for _ in range(n-1)]
counts = list(map(int, input().split()))

graph = defaultdict(list)
for a, b in paths:
    graph[a].append(b)
visited = [False] * (n + 1)

result = dfs(1, graph, counts, visited)
print(result)

Test 1

Group: 1, 2

Verdict: ACCEPTED

Test 2

Group: 1, 2

Verdict: ACCEPTED

Test 3

Group: 1, 2

Verdict: ACCEPTED

Test 4

Group: 2

Verdict: ACCEPTED

Test 5

Group: 2

Verdict: ACCEPTED

Test 6

Group: 1, 2

Verdict: ACCEPTED

Test 7

Group: 2

Verdict: ACCEPTED

Test 8

Group: 1, 2

Verdict: ACCEPTED

Test 9

Group: 2

Verdict: ACCEPTED

Test 10

Group: 1, 2

Verdict: ACCEPTED

Test 11

Group: 2

Verdict: ACCEPTED

Test 12

Group: 1, 2

Verdict: ACCEPTED

Test 13

Group: 2

Verdict: ACCEPTED