Added 2 solutions

varunu28 · varunu28 · commit 88393191eb25 · 2019-07-05T17:59:49.000-07:00
diff --git a/Hard/Serialize and Deserialize N-ary Tree.java b/Hard/Serialize and Deserialize N-ary Tree.java
@@ -0,0 +1,70 @@
+/*
+// Definition for a Node.
+class Node {
+    public int val;
+    public List<Node> children;
+
+    public Node() {}
+
+    public Node(int _val,List<Node> _children) {
+        val = _val;
+        children = _children;
+    }
+};
+*/
+class Codec {
+
+    // Encodes a tree to a single string.
+    StringBuilder sb;
+    public String serialize(Node root) {
+        if (root == null) {
+            return "";
+        }
+        
+        sb = new StringBuilder();
+        serializeHelper(root);
+        
+        return sb.toString().substring(0, sb.length() - 1);
+    }
+    
+    private void serializeHelper(Node root) {        
+        if (root == null) {
+            return;
+        }
+        
+        sb.append(root.val).append(",").append(root.children.size()).append(",");
+        for (Node child : root.children) {
+            serializeHelper(child);
+        }
+    }
+
+    // Decodes your encoded data to tree.
+    public Node deserialize(String data) {
+        if (data == null || data.length() == 0) {
+            return null;
+        }
+        
+        Queue<String> queue = new LinkedList<>();
+        queue.addAll(Arrays.asList(data.split(",")));
+        
+        return deserializeHelper(queue);
+    }
+    
+    private Node deserializeHelper(Queue<String> queue) {
+        Node root = new Node();
+        root.val = Integer.parseInt(queue.remove());
+        int size = Integer.parseInt(queue.remove());
+        
+        root.children = new ArrayList<>(size);
+        
+        for (int i = 0; i < size; i++) {
+            root.children.add(deserializeHelper(queue));
+        }
+        
+        return root;
+    }
+}
+
+// Your Codec object will be instantiated and called as such:
+// Codec codec = new Codec();
+// codec.deserialize(codec.serialize(root));
diff --git a/Medium/Reconstruct Itinerary.java b/Medium/Reconstruct Itinerary.java
@@ -0,0 +1,25 @@
+class Solution {
+    public List<String> findItinerary(List<List<String>> tickets) {
+        Map<String, PriorityQueue<String>> map = new HashMap<>();
+        for (List<String> ticket : tickets) {
+            map.computeIfAbsent(ticket.get(0), k -> new PriorityQueue<>()).add(ticket.get(1));
+        }
+
+        List<String> route = new ArrayList<>();
+        Stack<String> stack = new Stack<>();
+
+        stack.push("JFK");
+
+        while (!stack.isEmpty()) {
+            while (map.containsKey(stack.peek()) && !map.get(stack.peek()).isEmpty()) {
+                stack.push(map.get(stack.peek()).poll());
+            }
+
+            route.add(stack.pop());
+        }
+
+        Collections.reverse(route);
+
+        return route;
+    }
+}
