leetcode-13双周赛-1257-最小公共区域

题目描述：

方法：

class Solution(object):
    def findSmallestRegion(self, regions, region1, region2):
        parent = {}
        for row in regions:
            top = row.pop(0)
            for bot in row:
                parent[bot] = top

        seen = {region1}
        while region1 in parent:
            region1 = parent[region1]
            seen.add(region1)

        while region2 not in seen:
            region2 = parent[region2]
        return region2