1108 Defanging an IP Address IP 地址无效化

Description:
Given a valid (IPv4) IP address, return a defanged version of that IP address.

A defanged IP address replaces every period "." with "[.]".

Example:

Example 1:

Input: address = "1.1.1.1"
Output: "1[.]1[.]1[.]1"

Example 2:

Input: address = "255.100.50.0"
Output: "255[.]100[.]50[.]0"

Constraints:

The given address is a valid IPv4 address.

题目描述:
给你一个有效的 IPv4 地址 address，返回这个 IP 地址的无效化版本。

所谓无效化 IP 地址，其实就是用 "[.]" 代替了每个 "."。

示例 :

示例 1：

输入：address = "1.1.1.1"
输出："1[.]1[.]1[.]1"

示例 2：

输入：address = "255.100.50.0"
输出："255[.]100[.]50[.]0"

提示：

给出的 address 是一个有效的 IPv4 地址

思路:
遍历字符串, 按照题目要求把 “.”替换成 “[.]”即可
时间复杂度O(n), 空间复杂度O(1)

代码:
C++:

class Solution 
{
public:
    string defangIPaddr(string address) 
    {
        for (int i = address.size() - 1; i > -1; --i) if (address[i] == '.') address.replace(i, 1, "[.]");
        return address;
    }
};

Java:

class Solution {
    public String defangIPaddr(String address) {
        return address.replaceAll("\\.", "[.]");
    }
}

Python:

class Solution:
    def defangIPaddr(self, address: str) -> str:
        return address.replace(r'.', '[.]')