add: SerializeAndDeserializeABinaryTree

Author: Jer3myYu

java/Trees/SerializeAndDeserializeABinaryTree.java

@@ -0,0 +1,64 @@
+import java.lang.StringBuilder;
+import java.util.Arrays;
+import java.util.LinkedList;
+import java.util.Queue;
+
+import DS.TreeNode;
+
+/*
+    // Definition of TreeNode:
+    class TreeNode {
+        public int val;
+        public TreeNode left;
+        public TreeNode right;
+        public TreeNode(int val) {
+            this.val = val;
+        }
+    }
+ */
+
+public class SerializeAndDeserializeABinaryTree {
+    public String serialize(TreeNode root) {
+        // Perform a preorder traversal to add node values to a list, then convert the
+        // list to a string.
+        StringBuilder serializedList = new StringBuilder();
+        preorderSerialize(root, serializedList);
+        return serializedList.toString();
+    }
+
+    // Helper function to perform serialization through preorder traversal.
+    private void preorderSerialize(TreeNode node, StringBuilder serializedList) {
+        // Base case: mark null nodes as '#'.
+        if (node == null) {
+            serializedList.append("#").append(",");
+            return;
+        }
+        // Preorder traversal processes the current node first, then the left and right
+        // children.
+        serializedList.append(node.val).append(",");
+        preorderSerialize(node.left, serializedList);
+        preorderSerialize(node.right, serializedList);
+    }
+
+    public TreeNode deserialize(String data) {
+        // Obtain the node values by splitting the string using the comma delimiter.
+        Queue<String> nodeValues = new LinkedList<>();
+        nodeValues.addAll(Arrays.asList(data.split(",")));
+        return buildTree(nodeValues);
+    }
+
+    // Helper function to construct the tree using preorder traversal.
+    private TreeNode buildTree(Queue<String> values) {
+        String val = values.poll();
+        // Base case: '#' indicates a null node.
+        if (val.equals("#")) {
+            return null;
+        }
+        // Use preorder traversal processes the current node first, then the left and 
+        // right children.
+        TreeNode node = new TreeNode(Integer.valueOf(val));
+        node.left = buildTree(values);
+        node.right = buildTree(values);
+        return node;
+    }
+}