python

You are given a list of puzzle pieces. Each piece is represented as a tuple of two strings, one for each end of the piece. One example of such a piece is (ABC, XYZ). This piece can be used either as is or rotated. When the previous item is rotated, it becomes (XYZ, ABC). To complete a puzzle, all elements must be used and put in a form where the ends of each two consecutive pieces match. Example: (ABC, XYZ), (XYZ, UV), (UV,L), (L, A), (A, A) Implement the function solve_puzzle (pieces). An example pieces list is [("A", "B"), ("B", "C"), ("B", "B"), ("B", "C")]. One possible result is: [("A", "B"), ("B", "B"), ("B", "C"), ("C", "B")] . When the puzzle can't be solved, return None