1108. Defanging an IP Address

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

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

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.

string defangIPaddr(string address) { // time: O(n); space: O(n)
    string res;
    for (char ch : address) {
        if (ch >= '0' && ch <= '9') res += ch;
        else if (ch == '.') res += "[.]";
    }
    return res;
}