From a6c95b78e80f754dc901747046e06008710a639f Mon Sep 17 00:00:00 2001
From: jianghongcheng <35664721+jianghongcheng@users.noreply.github.com>
Date: Sat, 27 May 2023 19:21:17 -0500
Subject: [PATCH] =?UTF-8?q?Update=200491.=E9=80=92=E5=A2=9E=E5=AD=90?=
 =?UTF-8?q?=E5=BA=8F=E5=88=97.md?=
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---
 problems/0491.递增子序列.md | 24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/problems/0491.递增子序列.md b/problems/0491.递增子序列.md
index a805a262..50cb9918 100644
--- a/problems/0491.递增子序列.md
+++ b/problems/0491.递增子序列.md
@@ -272,23 +272,24 @@ class Solution {
 class Solution:
     def findSubsequences(self, nums):
         result = []
-        self.backtracking(nums, 0, [], result)
+        path = []
+        self.backtracking(nums, 0, path, result)
         return result
-
+    
     def backtracking(self, nums, startIndex, path, result):
         if len(path) > 1:
-            result.append(path[:])  # 将当前路径的副本加入结果集
+            result.append(path[:])  # 注意要使用切片将当前路径的副本加入结果集
+            # 注意这里不要加return，要取树上的节点
         
-        used = set()  # 使用集合来进行去重操作
+        uset = set()  # 使用集合对本层元素进行去重
         for i in range(startIndex, len(nums)):
-            if path and nums[i] < path[-1]:
-                continue  # 如果当前元素小于上一个元素，则跳过当前元素
+            if (path and nums[i] < path[-1]) or nums[i] in uset:
+                continue
             
-            if nums[i] in used:
-                continue  # 如果当前元素已经使用过，则跳过当前元素
-            
-            used.add(nums[i])  # 标记当前元素已经使用过
-            self.backtracking(nums, i + 1, path + [nums[i]], result)
+            uset.add(nums[i])  # 记录这个元素在本层用过了，本层后面不能再用了
+            path.append(nums[i])
+            self.backtracking(nums, i + 1, path, result)
+            path.pop()
 
 ```
 回溯 利用哈希表去重
@@ -314,6 +315,7 @@ class Solution:
             self.backtracking(nums, i + 1, path, result)
             path.pop()
 
+
 ```
 ### Go