图BFS遍历

def solve(____):
    from collections import defaultdict, deque
    graph = defaultdict(____)
    for e in edges.split(____):
        u, v = map(int, e.split(____))
        graph[u].append(____)
        graph[v].append(____)
    for k in graph:
        graph[k].sort()
    visited = {int(____)}
    queue = deque([int(____)])
    result = []
    while queue:
        node = queue.popleft()
        result.append(____)
        for neighbor in graph[node]:
            if neighbor not in visited:
                visited.add(____)
                queue.append(____)
    print('____'.join(map(____)))