LeetCode 1436. 旅行终点站

示例 1：

输入：paths = [["London","New York"],["New York","Lima"],["Lima","Sao Paulo"]]
输出："Sao Paulo" 
解释：从 "London" 出发，最后抵达终点站 "Sao Paulo" 。本次旅行的路线是 "London" -> "New York" -> "Lima" -> "Sao Paulo" 。
示例 2：

输入：paths = [["B","C"],["D","B"],["C","A"]]
输出："A"
解释：所有可能的线路是：
"D" -> "B" -> "C" -> "A". 
"B" -> "C" -> "A". 
"C" -> "A". 
"A". 
显然，旅行终点站是 "A" 。
示例 3：

输入：paths = [["A","Z"]]
输出："Z"

class Solution:
    def destCity(self, paths: List[List[str]]) -> str:
        # 用字典形式存储地点
        resDict = dict()
        for iList in paths:
            #如果地点存在，就删除【因为本来就是对数存在】，不存在就添加，并记录是起点还是终点
            for index,val in enumerate(iList):
                if val in resDict:
                    del resDict[val]
                else:
                    resDict[val] = index
        for key,val in resDict.items():
            #val== 1为终点位置
            if val == 1:
                return key




if __name__ == '__main__':
    paths = [["London","New York"],["New York","Lima"],["Lima","Sao Paulo"]]
    ret = Solution().destCity(paths)
    print(ret)