[ PS ] : Serialize and Deserialize Binary Tree

Author: uraflower

serialize-and-deserialize-binary-tree/uraflower.js

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+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val) {
+ *     this.val = val;
+ *     this.left = this.right = null;
+ * }
+ */
+
+const NULL_SIGN = 'X';
+
+/**
+ * Encodes a tree to a single string.
+ * 시간복잡도: O(n)
+ * 공간복잡도: O(h) (h: 재귀 스택 깊이 즉 트리 높이)
+ * @param {TreeNode} root
+ * @return {string}
+ */
+const serialize = function (root) {
+    const result = [];
+
+    function traverse(root) {
+        result.push(root?.val ?? NULL_SIGN);
+        if (!root) {
+            return;
+        }
+        traverse(root.left);
+        traverse(root.right);
+    }
+
+    traverse(root);
+    return result.join(',');
+};
+
+/**
+ * Decodes your encoded data to tree.
+ * 시간복잡도: O(n)
+ * 공간복잡도: O(h) (h: 재귀 스택 깊이 즉 트리 높이)
+ * @param {string} data
+ * @return {TreeNode}
+ */
+const deserialize = function (data) {
+    const splited = data.split(',');
+    let i = 0;
+
+    function makeTree() {
+        if (splited[i] === NULL_SIGN) {
+            return null;
+        }
+
+        const node = new TreeNode(Number(splited[i]));
+        i += 1;
+        node.left = makeTree();
+        i += 1;
+        node.right = makeTree();
+
+        return node;
+    }
+
+    return makeTree();
+};
+
+/**
+ * Your functions will be called as such:
+ * deserialize(serialize(root));
+ */