diff --git a/problems/0347.前K个高频元素.md b/problems/0347.前K个高频元素.md
index 0b8fd2d7..8bd774e9 100644
--- a/problems/0347.前K个高频元素.md
+++ b/problems/0347.前K个高频元素.md
@@ -142,7 +142,7 @@ class Solution {
 
         Set<Map.Entry<Integer, Integer>> entries = map.entrySet();
         // 根据map的value值正序排，相当于一个小顶堆
-        PriorityQueue<Map.Entry<Integer, Integer>> queue = new PriorityQueue<>((o1, o2) -> o2.getValue() - o1.getValue());
+        PriorityQueue<Map.Entry<Integer, Integer>> queue = new PriorityQueue<>((o1, o2) -> o1.getValue() - o2.getValue());
         for (Map.Entry<Integer, Integer> entry : entries) {
             queue.offer(entry);
             if (queue.size() > k) {
diff --git a/problems/二叉树的递归遍历.md b/problems/二叉树的递归遍历.md
index 45b576e7..4beed650 100644
--- a/problems/二叉树的递归遍历.md
+++ b/problems/二叉树的递归遍历.md
@@ -116,19 +116,19 @@ Java：
 ```Java
 // 前序遍历·递归·LC144_二叉树的前序遍历
 class Solution {
-    ArrayList<Integer> preOrderReverse(TreeNode root) {
-        ArrayList<Integer> result = new ArrayList<Integer>();
-        preOrder(root, result);
+    public List<Integer> preorderTraversal(TreeNode root) {
+        List<Integer> result = new ArrayList<Integer>();
+        preorder(root, result);
         return result;
     }
 
-    void preOrder(TreeNode root, ArrayList<Integer> result) {
+    public void preorder(TreeNode root, List<Integer> result) {
         if (root == null) {
             return;
         }
-        result.add(root.val);           // 注意这一句
-        preOrder(root.left, result);
-        preOrder(root.right, result);
+        result.add(root.val);
+        preorder(root.left, result);
+        preorder(root.right, result);
     }
 }
 // 中序遍历·递归·LC94_二叉树的中序遍历