diff --git a/include/s0093_restore_ip_addresses.hpp b/include/s0093_restore_ip_addresses.hpp
new file mode 100644
index 0000000..a513da4
--- /dev/null
+++ b/include/s0093_restore_ip_addresses.hpp
@@ -0,0 +1,14 @@
+#ifndef S0093_RESTORE_IP_ADDRESSES_HPP
+#define S0093_RESTORE_IP_ADDRESSES_HPP
+
+#include <string>
+#include <vector>
+
+using namespace std;
+
+class S0093 {
+ public:
+  vector<string> restoreIpAddresses(string s);
+};
+
+#endif
diff --git a/notes/src/backtrack.md b/notes/src/backtrack.md
index e673b26..abb238b 100644
--- a/notes/src/backtrack.md
+++ b/notes/src/backtrack.md
@@ -28,10 +28,15 @@ void backtrack(NodeState &node, vector<NodeState> &result, int para1, int para2,
     return;
   }
 
+  // 剪枝
+  // 当现在的节点不可能出现我们想要的结果时，直接跳过。
+  if (/* out of scope */) {
+    return;
+  }
+
   // 遍历该节点的所有子节点，即遍历下一层
   for (...) {
-    // 剪枝
-    // 当现在的节点不可能出现我们想要的结果时，直接跳过。
+    // 剪枝也可以在 for 循环中完成
     if (/* out of scope */) {
       continue;
     }
diff --git a/notes/src/split.md b/notes/src/split.md
index 713ddae..bd6a400 100644
--- a/notes/src/split.md
+++ b/notes/src/split.md
@@ -3,3 +3,5 @@
 ## [131. 分割回文串](https://leetcode.cn/problems/palindrome-partitioning/)
 
 ![](https://paste.sainnhe.dev/FHTE.jpg)
+
+## [93. 复原 IP 地址](https://leetcode.cn/problems/restore-ip-addresses/)
diff --git a/src/s0093_restore_ip_addresses.cpp b/src/s0093_restore_ip_addresses.cpp
new file mode 100644
index 0000000..b42fe44
--- /dev/null
+++ b/src/s0093_restore_ip_addresses.cpp
@@ -0,0 +1,55 @@
+#include "s0093_restore_ip_addresses.hpp"
+
+bool isValidIpAddressSegment(const string &s, int begin, int end) {
+  if (begin > end) {
+    return false;
+  }
+  if (s[begin] == '0' && begin != end) {  // 0开头的数字不合法
+    return false;
+  }
+  int num = 0;
+  for (int i = begin; i <= end; i++) {
+    if (s[i] > '9' || s[i] < '0') {  // 遇到非数字字符不合法
+      return false;
+    }
+    num = num * 10 + (s[i] - '0');
+    if (num > 255) {  // 如果大于255了不合法
+      return false;
+    }
+  }
+  return true;
+}
+
+void restoreIpAddressesDFS(vector<int> &dots, vector<string> &result, string &s,
+                           int startIndex) {
+  // 结束条件
+  if (dots.size() == 4 && startIndex == s.length()) {
+    string ip = s.substr(0, dots[0] + 1) + "." +
+                s.substr(dots[0] + 1, dots[1] - dots[0]) + "." +
+                s.substr(dots[1] + 1, dots[2] - dots[1]) + "." +
+                s.substr(dots[2] + 1, dots[3] - dots[2]);
+    result.push_back(ip);
+  }
+
+  // 剪枝
+  // 如果已经分成了四段，就没必要再分了
+  if (dots.size() == 4) {
+    return;
+  }
+
+  // 遍历当前节点的下一层
+  for (int i = startIndex; i < startIndex + 3; ++i) {
+    if (isValidIpAddressSegment(s, startIndex, i)) {
+      dots.push_back(i);
+      restoreIpAddressesDFS(dots, result, s, i + 1);
+      dots.pop_back();
+    }
+  }
+}
+
+vector<string> S0093::restoreIpAddresses(string s) {
+  vector<string> result{};
+  vector<int> dots{};
+  restoreIpAddressesDFS(dots, result, s, 0);
+  return result;
+}