【LeetCode 10-1】一 旅行终点站

在这里利用2个hash表，一个存储出现了几次，一个存在在行list中的位置，0或者1

class Solution:
    def destCity(self, paths: List[List[str]]) -> str:
        hashMap = {}
        hashIndex = {}
        for i in range(len(paths)):
            pathSingle = paths[i]
            icnt = 0
            for idx in pathSingle:
                icnt += 1
                hashIndex[idx] = icnt
                if idx not in hashMap:
                    hashMap[idx] = 1
                else:
                    hashMap[idx] += 1

        for keyx in hashMap:
            if hashMap[keyx] == 1 and hashIndex[keyx] == 2:
                return keyx

pass: 官方的解答

		cityA = {path[0] for path in paths}
        #print(cityA)
        #print(path[1] for path in paths if path[1] not in cityA)
        return next(path[1] for path in paths if path[1] not in cityA)  # path[1] 表示第二个位置
        # 返回的是一个可迭代对象