LeetCode 1743. Restore the Array From Adjacent Pairs 求助

我正在解决Restore the Array From Adjacent Pairs - LeetCode，我的 solution 并没有 pass 所有的 test case ，想问一下我的 solution 有什么问题，自己完全找不出来。?

Thanks in advance.

class Solution:
    def restoreArray(self, adjacentPairs: List[List[int]]) -> List[int]:
        num_to_neighbors = defaultdict(list)
        for u, v in adjacentPairs:
            num_to_neighbors[u].append(v)
            num_to_neighbors[v].append(u)
        
        head, next_num = next((num, neighbors[0]) for num, neighbors in num_to_neighbors.items() if len(neighbors) == 1)
        res = [head]
        while next_num:
            res.append(next_num)
            next_num = next((neighbor for neighbor in num_to_neighbors[next_num] if neighbor != res[-2]), None)
        return res