332. Reconstruct Itinerary - LeetCode Solution

class Solution:
    def findItinerary(self, tickets: List[List[str]]) -> List[str]:
        def d(c):
            while(len(g[c]) > 0):
                d(g[c].pop(0))
            r.insert(0, c) 
            
        g = collections.defaultdict(list)
        for u, v in (tickets):
            
            g[u].append(v)
            
            g[u].sort()
            
        r=[]      
        
        d("JFK")
        
        return r