feat: 二叉树章节结束

Author: sl1673495

二叉树/二叉搜索树中第K小的元素.js

@@ -0,0 +1,34 @@
+/**
+ * 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 count = 0
+  let finded
+
+  let dfs = (node) => {
+    if (!node) {
+      return
+    }
+    dfs(node.left)
+    count++
+    if (count === k) {
+      finded = node.val
+      return
+    }
+    dfs(node.right)
+  }
+
+  dfs(root)
+
+  return finded
+}

二叉树/将有序数组转为二叉搜索树.js

@@ -0,0 +1,13 @@
+let sortedArrayToBST = function (nums) {
+  let n = nums.length
+  if (!n) {
+      return null
+  }
+  let mid = Math.floor(n / 2)
+  let root = new TreeNode(nums[mid])
+
+  root.left = sortedArrayToBST(nums.slice(0, mid))
+  root.right = sortedArrayToBST(nums.slice(mid + 1, n))
+
+  return root
+};