@@ -1,25 +1,31 @@
 class Solution {
-public int[] restoreArray(int[][] adjacentPairs) {
-Map<Integer, List<Integer>> map = new HashMap<>();
-for (int[] pair : adjacentPairs) {
-map.computeIfAbsent(pair[0], k -> new ArrayList<>()).add(pair[1]);
-map.computeIfAbsent(pair[1], k -> new ArrayList<>()).add(pair[0]);
+public int[] restoreArray(int[][] adjacentPairs) {
+int n = adjacentPairs.length + 1;
+Map<Integer, List<Integer>> map = new HashMap<>();
+for (int[] pair : adjacentPairs) {
+map.computeIfAbsent(pair[0], k -> new ArrayList<>()).add(pair[1]);
+map.computeIfAbsent(pair[1], k -> new ArrayList<>()).add(pair[0]);
+}
+Queue<Integer> queue = new LinkedList<>();
+int firstElement = map.entrySet()
+.stream()
+.filter(entry -> entry.getValue().size() == 1)
+.map(Map.Entry::getKey)
+.findFirst()
+.orElse(-1);
+queue.add(firstElement);
+Set<Integer> set = new HashSet<>();
+int[] result = new int[n];
+int idx = 0;
+while (!queue.isEmpty()) {
+int removed = queue.remove();
+if (set.contains(removed)) {
+continue;
+}
+result[idx++] = removed;
+set.add(removed);
+queue.addAll(map.get(removed));
+}
+return result;
 }
-int head = map.keySet().stream().filter(k -> map.get(k).size() == 1).findFirst().orElse(-1);
-Set<Integer> visited = new HashSet<>();
-int[] result = new int[map.size()];
-int idx = 0;
-Queue<Integer> queue = new LinkedList<>();
-queue.add(head);
-while (!queue.isEmpty()) {
-int removed = queue.remove();
-if (visited.contains(removed)) {
-continue;
-}
-result[idx++] = removed;
-visited.add(removed);
-queue.addAll(map.get(removed));
-}
-return result;
-}
 }