Capture the Pawns Problem in Java

"Capture the Pawns" is a classic chessboard problem that challenges programmers to develop a solution for finding the minimum number of moves required to capture all pawns on a given chessboard. In this problem, a chessboard of size N x N is considered, and the task is to determine the optimal sequence of moves to capture each pawn while adhering to the rules of chess movement.

Approach:

When it's the white pawn's turn, the game checks if it's located on the 8th row. If so, it signifies a win for Black, since the white pawn cannot make any more moves. Similarly, if the black pawn's turn comes and it's on the 1st row, this results in a victory for White, as the black pawn has no remaining moves.

A check is made for adjacency with the black pawn diagonally during the white pawn's turn. If adjacent, the white pawn captures the black pawn, resulting in a win for the White; otherwise, the white pawn moves forward one step if the destination is unoccupied. A similar process is applied during the black pawn's turn, with adjacency checks and forward movement, potentially leading to a win for the black or a loss if no valid moves are available.

Algorithm:

Step 1: Set the initial positions of the white pawn (rowWhite, colWhite) and the black pawn (rowBlack, colBlack).

Step 2: Initialize counters for the number of moves for white and black (whiteMoves, blackMoves).

Step 3: Set a boolean variable to control the turn-based moves (isWhiteTurn = true).

Step 4: Enter a loop that alternates between white and black moves until a winner is determined.

Step 5: Check if it's the white player's turn (isWhiteTurn is true). Check if the white pawn can move forward (rowWhite != 8).

• If yes, check if the white pawn can capture the black pawn (rowBlack == rowWhite + 1 and colBlack is adjacent), then return that white wins.
• If not, move the white pawn forward (increment rowWhite). If the white pawn reaches the end of the board (rowWhite == 8), return that white loses.

Step 6: Check if it's the black player's turn (isWhiteTurn is false). Check if the black pawn can move forward (rowBlack != 1).

• If yes, check if the black pawn can capture the white pawn (rowBlack == rowWhite + 1 and colBlack is adjacent). If true, return that white loses.
• If not, move the black pawn forward (decrement rowBlack). If the black pawn reaches the end of the board (rowBlack == 1), return that white wins.

Step 7: After each complete turn (white and black move), toggle the turn (isWhiteTurn = !isWhiteTurn).

Step 8: After the Loop, check if whiteMoves are greater than blackMoves.

• If true, return that white wins.
• If false, return that it's a draw or some other outcome.

Implementation:

Filename: ChessGame.java

Output:

White wins by capturing Black's pawn!

Time Complexity: The code has a time complexity of O(n) due to the Loop, where n represents the number of rows on the chessboard.

Space Complexity: The space complexity is O(1) as the amount of extra space used by the algorithm remains constant regardless of the input size.