图DFS遍历

def solve(____):
    from collections import defaultdict
    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 = set()
    result = []
    def dfs(____):
        visited.add(____)
        result.append(____)
        for neighbor in graph[node]:
            if neighbor not in visited:
                dfs(____)
    dfs(int(____))
    print('____'.join(map(____)))