From a22185ce4c173bfa78d22a5ef1cbfd59857ef858 Mon Sep 17 00:00:00 2001
From: huangge1199 <huangge1199@hotmail.com>
Date: Fri, 5 Feb 2021 13:15:08 +0800
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---
 .../leet/Official/t20210204/KthSmallest.java  | 27 +++++++++++++++++++
 .../leet/study/t20210204/KthSmallest.java     | 25 +++++++++++++++++
 2 files changed, 52 insertions(+)
 create mode 100644 LeetCode/src/main/java/com/code/leet/Official/t20210204/KthSmallest.java
 create mode 100644 LeetCode/src/main/java/com/code/leet/study/t20210204/KthSmallest.java

diff --git a/LeetCode/src/main/java/com/code/leet/Official/t20210204/KthSmallest.java b/LeetCode/src/main/java/com/code/leet/Official/t20210204/KthSmallest.java
new file mode 100644
index 0000000..ae2af27
--- /dev/null
+++ b/LeetCode/src/main/java/com/code/leet/Official/t20210204/KthSmallest.java
@@ -0,0 +1,27 @@
+package com.code.leet.Official.t20210204;
+
+import com.code.leet.entiy.TreeNode;
+
+import java.util.ArrayList;
+import java.util.LinkedList;
+import java.util.List;
+
+/**
+ * 给定一个二叉搜索树的根节点 root ，和一个整数 k ，请你设计一个算法查找其中第 k 个最小元素（从 1 开始计数）。
+ */
+public class KthSmallest {
+
+    public int kthSmallest(TreeNode root, int k) {
+        LinkedList<TreeNode> stack = new LinkedList<TreeNode>();
+
+        while (true) {
+            while (root != null) {
+                stack.add(root);
+                root = root.left;
+            }
+            root = stack.removeLast();
+            if (--k == 0) return root.val;
+            root = root.right;
+        }
+    }
+}
diff --git a/LeetCode/src/main/java/com/code/leet/study/t20210204/KthSmallest.java b/LeetCode/src/main/java/com/code/leet/study/t20210204/KthSmallest.java
new file mode 100644
index 0000000..ded69de
--- /dev/null
+++ b/LeetCode/src/main/java/com/code/leet/study/t20210204/KthSmallest.java
@@ -0,0 +1,25 @@
+package com.code.leet.study.t20210204;
+
+import com.code.leet.entiy.TreeNode;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class KthSmallest {
+
+    public int kthSmallest(TreeNode root, int k) {
+        List<Integer> nums = getList(root, new ArrayList<>());
+        return nums.get(k - 1);
+    }
+
+    private List<Integer> getList(TreeNode root, List<Integer> list) {
+        if(root==null){
+            return list;
+        }
+        getList(root.left,list);
+        list.add(root.val);
+        getList(root.right,list);
+
+        return list;
+    }
+}