Complete Leetcode 93

Author: yuchia0221

Backtracking/93-RestoreIPAddresses/README.md

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+# Restore IP Addresses
+
+Problem can be found in [here](https://leetcode.com/problems/restore-ip-addresses/)!
+
+### [Solution](/Backtracking/93-RestoreIPAddresses/solution.py): Backtracking
+
+```python
+def restoreIpAddresses(s: str) -> List[str]:
+    def dfs(start: int, candidate: List[str]) -> None:
+        if start == len(s):
+            if len(candidate) == 4:
+                result.append(".".join(candidate))
+            return
+
+        if s[start] == "0":
+            dfs(start+1, candidate+["0"])
+            return
+
+        for end in range(start+1, min(start+4, len(s)+1)):
+            address = s[start:end]
+            if 0 <= int(address) <= 255:
+                dfs(end, candidate+[address])
+
+    result = []
+    dfs(0, [])
+    return result
+```
+
+Time Complexity: ![O(m^n)](<https://latex.codecogs.com/svg.image?\inline&space;O(m^n)>), Space Complexity: ![O(m*n)](<https://latex.codecogs.com/svg.image?\inline&space;O(m*n)>), where n is the number of splits and m is the digits of each integer.

Backtracking/93-RestoreIPAddresses/solution.py

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+from typing import List
+
+
+class Solution:
+    def restoreIpAddresses(self, s: str) -> List[str]:
+        def dfs(start: int, candidate: List[str]) -> None:
+            if start == len(s):
+                if len(candidate) == 4:
+                    result.append(".".join(candidate))
+                return
+
+            if s[start] == "0":
+                dfs(start+1, candidate+["0"])
+                return
+
+            for end in range(start+1, min(start+4, len(s)+1)):
+                address = s[start:end]
+                if 0 <= int(address) <= 255:
+                    dfs(end, candidate+[address])
+
+        result = []
+        dfs(0, [])
+        return result