Given the position of one of your pawns on a chessboard, return an array of all the valid squares it can move to in ascending order.
A standard chessboard is 8x8, with columns labeled A through H (left to right) and rows labeled 1 through 8 (bottom to top). It looks like this:
| A8 | B8 | C8 | D8 | E8 | F8 | G8 | H8 |
|---|
| A7 | B7 | C7 | D7 | E7 | F7 | G7 | H7 |
| A6 | B6 | C6 | D6 | E6 | F6 | G6 | H6 |
| A5 | B5 | C5 | D5 | E5 | F5 | G5 | H5 |
| A4 | B4 | C4 | D4 | E4 | F4 | G4 | H4 |
| A3 | B3 | C3 | D3 | E3 | F3 | G3 | H3 |
| A2 | B2 | C2 | D2 | E2 | F2 | G2 | H2 |
| A1 | B1 | C1 | D1 | E1 | F1 | G1 | H1 |
For this challenge:
- You are the player on the bottom of the board.
- Pawns can only move one square “up”.
- Unless the pawn is in the starting row (row 2), then it can move one or two squares up.
For example, given "D4", return ["D5"], the only square your pawn can move to.
Given "B2", return ["B3", "B4"], because it’s on the starting row and needs to be in ascending order.