From 75e1bb2e7ba1c5334b30068882db8c27cf078982 Mon Sep 17 00:00:00 2001
From: Asterisk <44215173+casnz1601@users.noreply.github.com>
Date: Thu, 21 Oct 2021 12:54:24 +0800
Subject: [PATCH] =?UTF-8?q?Update=200031.=E4=B8=8B=E4=B8=80=E4=B8=AA?=
 =?UTF-8?q?=E6=8E=92=E5=88=97.md?=
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新增python代码：
抛砖引玉：因题目要求“必须原地修改，只允许使用额外常数空间”，python内置sorted函数以及数组切片+sort()无法使用，故选择另一种算法暂且提供一种python思路
---
 problems/0031.下一个排列.md | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/problems/0031.下一个排列.md b/problems/0031.下一个排列.md
index 9efcb06a..470c354d 100644
--- a/problems/0031.下一个排列.md
+++ b/problems/0031.下一个排列.md
@@ -122,6 +122,33 @@ class Solution {
 ## Python
 
 ```python
+class Solution:
+  '''
+  抛砖引玉：因题目要求“必须原地修改，只允许使用额外常数空间”，python内置sorted函数以及数组切片+sort()无法使用。  
+  故选择另一种算法暂且提供一种python思路
+  '''
+    def nextPermutation(self, nums: List[int]) -> None:
+        """
+        Do not return anything, modify nums in-place instead.
+        """
+        length = len(nums)
+        for i in range(length-1, 0, -1):
+            if nums[i-1] < nums[i]:
+                for j in range(length-1, 0, -1):
+                    if nums[j] > nums[i-1]:
+                        nums[i-1], nums[j] = nums[j], nums[i-1]
+                        break
+                self.reverse(nums, i, length-1)
+                break
+        else:
+            # 若正常结束循环，则对原数组直接翻转
+            self.reverse(nums, 0, length-1)
+
+    def reverse(self, nums: List[int], low: int, high: int) -> None:
+        while low < high:
+            nums[low], nums[high] = nums[high], nums[low]
+            low += 1
+            high -= 1
 ```
 
 ## Go