题目描述
给定一个只包含数字的字符串，复原它并返回所有可能的 IP 地址格式。
示例:
代码语言：javascript复制输入: "25525511135"
输出: ["255.255.11.135", "255.255.111.35"]93. Restore IP Addresses
Given a string containing only digits, restore it by returning all possible valid IP address combinations.
Example:
代码语言：javascript复制Input: "25525511135"
Output: ["255.255.11.135", "255.255.111.35"]解题思路
IP的格式分析:
代码语言：javascript复制seg1.seg2.seg3.seg4seg都是1-3位数字; 然后 seg1 seg2 seg3 seg4 = 字符串的长度.
源代码
代码语言：javascript复制fun restoreIpAddresses(s: String): List<String> {
val result = mutableListOf<String>()
val ip = StringBuilder()
for (seg1 in 1..3) {
for (seg2 in 1..3) {
for (seg3 in 1..3) {
for (seg4 in 1..3) {
if (seg1 seg2 seg3 seg4 == s.length) {
val v1 = s.substring(0, seg1).toInt()
val v2 = s.substring(seg1, seg1 seg2).toInt()
val v3 = s.substring(seg1 seg2, seg1 seg2 seg3).toInt()
val v4 = s.substring(seg1 seg2 seg3).toInt()
if (v1 <= 255 && v2 <= 255 && v3 <= 255 && v4 <= 255) {
ip.append(v1).append(".")
.append(v2).append(".")
.append(v3).append(".")
.append(v4)
val sip = ip.toString()
if (sip.length == s.length 3) {
result.add(sip)
}
// clear StringBuilder, ready to next for loop use
ip.clear()
}
}
}
}
}
}
return result
}
fun main() {
val s = "25525511135"
val ans = restoreIpAddresses(s)
println(ans) // [255.255.11.135, 255.255.111.35]
}参考资料
https://leetcode-cn.com/problems/restore-ip-addresses/solution/kotlinyou-mei-bao-li-po-jie-fa-fu-yuan-ip-by-cheng/
来源：力扣（LeetCode） 链接：https://leetcode-cn.com/problems/restore-ip-addresses 著作权归领扣网络所有。商业转载请联系官方授权，非商业转载请注明出处。
