From 8a4b3b1636af1272e561db534f9a4ccbcec7e45f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E6=9E=97=E7=BB=B5=E7=A8=8B?=
 <gzlinjincheng@corp.netease.com>
Date: Fri, 17 Sep 2021 16:12:24 -0700
Subject: [PATCH] =?UTF-8?q?=E6=B7=BB=E5=8A=A00077.=E7=BB=84=E5=90=88python?=
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---
 problems/0077.组合.md | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/problems/0077.组合.md b/problems/0077.组合.md
index 9b44b572..c72adb83 100644
--- a/problems/0077.组合.md
+++ b/problems/0077.组合.md
@@ -368,6 +368,34 @@ class Solution {
 }
 ```
 
+Python2:
+```python
+class Solution(object):
+    def combine(self, n, k):
+        """
+        :type n: int
+        :type k: int
+        :rtype: List[List[int]]
+        """
+        result = []
+        path = []
+        def backtracking(n, k, startidx):
+            if len(path) == k:
+                result.append(path[:])
+                return
+
+            # 剪枝， 最后k - len(path)个节点直接构造结果，无需递归
+            last_startidx = n - (k - len(path)) + 1
+            result.append(path + [idx for idx in range(last_startidx, n + 1)])
+
+            for x in range(startidx, last_startidx):
+                path.append(x)
+                backtracking(n, k, x + 1)  # 递归
+                path.pop()  # 回溯
+
+        backtracking(n, k, 1)
+        return result
+```
 
 Python：
 ```python3