From d5b0e0ce587df7bb9c627bbad784b71d01098e36 Mon Sep 17 00:00:00 2001
From: Jijie LIU <liujijieseason@gmail.com>
Date: Wed, 16 Jun 2021 14:49:07 +0200
Subject: [PATCH] =?UTF-8?q?Update=2093.=E5=A4=8D=E5=8E=9FIP=E5=9C=B0?=
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---
 problems/0093.复原IP地址.md | 40 +++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/problems/0093.复原IP地址.md b/problems/0093.复原IP地址.md
index a8b9a215..c47896d9 100644
--- a/problems/0093.复原IP地址.md
+++ b/problems/0093.复原IP地址.md
@@ -338,6 +338,46 @@ class Solution(object):
         return ans```
 ```
 
+```python3
+class Solution:
+    def __init__(self) -> None:
+        self.s = ""
+        self.res = []
+
+    def isVaild(self, s: str) -> bool:
+        if len(s) > 1 and s[0] == "0":
+            return False
+
+        if 0 <= int(s) <= 255:
+            return True
+
+        return False
+
+    def backTrack(self, path: List[str], start: int) -> None:
+        if start == len(self.s) and len(path) == 4:
+            self.res.append(".".join(path))
+            return
+
+        for end in range(start + 1, len(self.s) + 1):
+            # 剪枝
+            # 保证切割完，s没有剩余的字符。
+            if len(self.s) - end > 3 * (4 - len(path) - 1):
+                continue
+            if self.isVaild(self.s[start:end]):
+                # 在参数处，更新状态，实则创建一个新的变量
+                # 不会影响当前的状态，当前的path变量没有改变
+                # 因此递归完不用path.pop()
+                self.backTrack(path + [self.s[start:end]], end)
+
+    def restoreIpAddresses(self, s: str) -> List[str]:
+        # prune
+        if len(s) > 3 * 4:
+            return []
+        self.s = s
+        self.backTrack([], 0)
+        return self.res
+```
+
 JavaScript： 
 
 ```js