day-20

libterty · libterty · commit 83d759b01421 · 2020-05-20T23:54:43.000+08:00
diff --git a/README.md b/README.md
@@ -20,3 +20,4 @@
     -   Day 17: [Find All Anagrams in a String Solution](https://github.com/libterty/leetcode-challenge/blob/master/src/may/day-seventeen/index.ts) :hear_no_evil:
     -   Day 18: [Permutation in String](https://github.com/libterty/leetcode-challenge/blob/master/src/may/day-eighteen/index.ts) :pig_nose:
     -   Day 19: [Online Stock Span](https://github.com/libterty/leetcode-challenge/blob/master/src/may/day-nighteen/index.ts) :pig_nose:
+    -   Day 20: [KTH smallest BST](https://github.com/libterty/leetcode-challenge/blob/master/src/may/day-twenty/index.ts) :pig_nose:
diff --git a/src/may/day-twenty/index.ts b/src/may/day-twenty/index.ts
@@ -0,0 +1,29 @@
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val, left, right) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.left = (left===undefined ? null : left)
+ *     this.right = (right===undefined ? null : right)
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @param {number} k
+ * @return {number}
+ */
+var kthSmallest = function (root, k) {
+    let result = [];
+    kHelper(root);
+    return result[k - 1];
+
+    function kHelper(node) {
+        if (!node) return;
+
+        if (result.length >= k) return;
+        kHelper(node.left);
+
+        if (result.length >= k) return;
+        result.push(node.val);
+        kHelper(node.right);
+    }
+};
