solve Kth Smallest Element in a BST solution

Author: HoonDongKang

kth-smallest-element-in-a-bst/HoonDongKang.ts

@@ -0,0 +1,34 @@
+/**
+ * [Problem]: [230] Kth Smallest Element in a BST
+ * (https://leetcode.com/problems/kth-smallest-element-in-a-bst/description/)
+ */
+
+class TreeNode {
+    val: number;
+    left: TreeNode | null;
+    right: TreeNode | null;
+    constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
+        this.val = val === undefined ? 0 : val;
+        this.left = left === undefined ? null : left;
+        this.right = right === undefined ? null : right;
+    }
+}
+
+function kthSmallest(root: TreeNode | null, k: number): number {
+    //시간복잡도 O(n)
+    //공간복잡도 O(n)
+    function inOrderFunc(root: TreeNode | null, k: number): number {
+        const values: number[] = [];
+
+        function dfs(node: TreeNode | null) {
+            if (!node) return;
+            dfs(node.left);
+            values.push(node.val);
+            dfs(node.right);
+        }
+
+        dfs(root);
+
+        return values[k - 1];
+    }
+}