Which king of Egypt attacked Jerusalem in the fifth year of Rehoboam?

Answer: Shishak

Shishak king of Egypt attacked Jerusalem and carried off the temple and palace treasures, including Solomon's gold shields.

“In the fifth year of Rehoboam’s reign, Shishak king of Egypt attacked Jerusalem. He seized the treasures of the house of the LORD and of the royal palace. He took everything, including all the gold shields that Solomon had made.”— 1 Kings 14:25-26 (BSB)