Evaluates string parsing and input-validation skills, including digit-only checks, delimiter-based splitting, numeric range enforcement, and edge-case handling. Commonly asked to assess attention to input formats and robustness in implementation; Category: Coding & Algorithms; Level: implementation-level (concrete string manipulation and validation).
Given a string s, determine whether it is a valid IPv4 address.
A valid IPv4 address:
.
):
x1.x2.x3.x4
[0, 255]
Examples:
"192.168.1.1"
,
"192.168.1.0"
"192.168.100.1.1"
(5 parts),
"192.1681.1"
(missing dot separation)
Write a function that returns True if s is a valid IPv4 address and False otherwise.