Reconstruct Itinerary

public class Solution {
    public List<String> findItinerary(String[][] tickets) {
        List<String> result = new ArrayList<>();
        if (tickets.length == 0 || tickets[0].length == 0) {
            return result;
        }
        Map<String, PriorityQueue<String>> iternary = new HashMap<>();
        for (String[] fromTo : tickets) {
            if (!iternary.containsKey(fromTo[0])) {
                iternary.put(fromTo[0], new PriorityQueue<>());
            }
            iternary.get(fromTo[0]).add(fromTo[1]);
        }
        
        Stack<String> stack = new Stack<>();
        stack.push("JFK");
        
        while (!stack.isEmpty()) {
            String current = stack.peek();
            if (iternary.containsKey(current) && iternary.get(current).size() > 0) {
                stack.push(iternary.get(current).poll());
            } else {
                result.add(0, stack.pop());
            }
        }
        return result;
    }
}