Given a string of digits, find all possible valid IP address combinations you can create by inserting dots. An IP address is valid if each segment is between 0 and 255.

You're given a string of characters and a limit on how many times each character can repeat consecutively. Build the lexicographically largest string possible while respecting this repeat limit.

In a town, find the 'judge' who is trusted by everyone else but doesn't trust anyone. You are given trust relationships; determine if a town judge exists and, if so, who they are.