Maze with Portals

You are given a 2D grid representing a maze. Each cell in the grid is represented by a character with the following meanings:

• S: The starting position.
• E: The exit position.
• #: A wall (impassable).
• .: An open path.
• A-Z: Portals. Each uppercase letter represents a portal. For any given letter, if it appears twice in the maze, stepping on one teleports you instantly to the other. The teleportation happens as part of the same move you step onto the portal cell.

You can move in the four cardinal directions (up, down, left, right) from any open cell (or from a portal cell after teleportation). Each move to an adjacent cell counts as one step, including stepping onto a portal cell (teleportation itself does not consume an extra step).

Write a function/method that takes the maze as input (e.g., as a list of strings or a 2D array) and returns the minimum number of steps required to reach the exit E from the starting point S. If there is no valid path, return -1.

Example:

Input maze:
[
  "S.#",
  "A.E",
  "#.A"
]

Explanation:
- Start at S (top left).
- One possible path: Step right, step down into portal A, teleport to the other A, then move right to reach E.

Output: 4

Constraints:

• The maze dimensions can vary (e.g., up to 100x100).
• Portals always appear in pairs if they are present (i.e., if a portal letter appears, it appears exactly twice).
• There is exactly one S and one E in the maze.

Design an efficient solution that computes the minimum number of steps from S to E.

Good luck!