< Back 1436. Destination City Given a list of paths where paths[0] is the starting city and paths[0] is the destination city, return the only city that is never a starting city, only a destination. To solve this we just use list comprehension to extract the start and destination cities, placing them each into two seperate sets. Then we use a set operation to calculate the difference between the destinations and the starts, returning the only city that is the only destination. The solution is as follows: class Solution: def destCity(self, paths: List[List[str]]) -> str: starts = set([start for start, _ in paths]) destinations = set([destination for _, destination in paths]) return list(destinations - starts)[0] _ Time Complexity: O(n) - We parse all paths. _ Space Complexity: O(n) - We create two sets of starts and destinations.