- Difficulty: Medium
- Tags: LeetCode, Medium, String, Backtracking, leetcode-93, O(1), LintCode
Problem
A valid IP address consists of exactly four integers separated by single dots. Each integer is between 0
and 255
(inclusive) and cannot have leading zeros.
- For example,
"0.1.2.201"
and"192.168.1.1"
are valid IP addresses, but"0.011.255.245"
,"192.168.1.312"
and"192.168@1.1"
are invalid IP addresses.
Given a string s
containing only digits, return all possible valid IP addresses that can be formed by inserting dots into s
. You are not allowed to reorder or remove any digits in s
. You may return the valid IP addresses in any order.
Example 1:
Input: s = "25525511135" Output: ["255.255.11.135","255.255.111.35"]
Example 2:
Input: s = "0000" Output: ["0.0.0.0"]
Example 3:
Input: s = "101023" Output: ["1.0.10.23","1.0.102.3","10.1.0.23","10.10.2.3","101.0.2.3"]
Constraints:
1 <= s.length <= 20
s
consists of digits only.