Envío 5610

Código

N = int(input())

tree = {}
memo = {}

for i in range(N - 1):
    treeData = input().split(' ')
    tree[treeData[1]] = treeData[0]

C = int(input())

for i in range(C):
    wasYes = False
    query = input().split(' ')
    ancestor = query[0]
    child = query[1]
    memo[child] = {}

    if ancestor == '0' or ancestor == child:
        print('Yes')
        continue

    try:
        parent = tree[child]
    except:
        parent = None

    while parent is not None:
        if parent == ancestor or (parent in memo and ancestor in memo[parent]):
            print('Yes')
            wasYes = True
            break

        memo[child][parent] = True

        try:
            parent = tree[parent]
        except:
            parent = None

    if not wasYes:
        print('No')