Introduction

In this blog post, we will explore how to solve the LeetCode problem "999" using AI. LeetCode is a popular platform for preparing for coding interviews, and with the help of AI tools like Chatmagic, we can generate solutions quickly and efficiently - helping you pass the interviews and get the job offer without having to study for months.

Problem Statement

You are given an 8 x 8 matrix representing a chessboard. There is exactly one white rook represented by 'R', some number of white bishops 'B', and some number of black pawns 'p'. Empty squares are represented by '.'. A rook can move any number of squares horizontally or vertically (up, down, left, right) until it reaches another piece or the edge of the board. A rook is attacking a pawn if it can move to the pawn's square in one move. Note: A rook cannot move through other pieces, such as bishops or pawns. This means a rook cannot attack a pawn if there is another piece blocking the path. Return the number of pawns the white rook is attacking. Example 1: Input: board = [[".",".",".",".",".",".",".","."],[".",".",".","p",".",".",".","."],[".",".",".","R",".",".",".","p"],[".",".",".",".",".",".",".","."],[".",".",".",".",".",".",".","."],[".",".",".","p",".",".",".","."],[".",".",".",".",".",".",".","."],[".",".",".",".",".",".",".","."]] Output: 3 Explanation: In this example, the rook is attacking all the pawns. Example 2: Input: board = [[".",".",".",".",".",".","."],[".","p","p","p","p","p",".","."],[".","p","p","B","p","p",".","."],[".","p","B","R","B","p",".","."],[".","p","p","B","p","p",".","."],[".","p","p","p","p","p",".","."],[".",".",".",".",".",".",".","."],[".",".",".",".",".",".",".","."]] Output: 0 Explanation: The bishops are blocking the rook from attacking any of the pawns. Example 3: Input: board = [[".",".",".",".",".",".",".","."],[".",".",".","p",".",".",".","."],[".",".",".","p",".",".",".","."],["p","p",".","R",".","p","B","."],[".",".",".",".",".",".",".","."],[".",".",".","B",".",".",".","."],[".",".",".","p",".",".",".","."],[".",".",".",".",".",".",".","."]] Output: 3 Explanation: The rook is attacking the pawns at positions b5, d6, and f5. Constraints: board.length == 8 board[i].length == 8 board[i][j] is either 'R', '.', 'B', or 'p' There is exactly one cell with board[i][j] == 'R'

Explanation

Here's a solution to the problem:

• Find the Rook: Locate the position of the white rook 'R' on the chessboard.
• Check in Four Directions: From the rook's position, check for pawns 'p' in each of the four directions (up, down, left, right). Stop checking in a direction when you encounter another piece ('B', 'R', 'p') or the edge of the board.

• Count Attacked Pawns: Increment the count of attacked pawns for each pawn found in a clear line of sight from the rook.

• Runtime Complexity: O(1), since we iterate at most 8 times in each direction.

• Storage Complexity: O(1).

Code

    def numRookCaptures(board):
    """
    Calculates the number of pawns the white rook is attacking on the chessboard.

    Args:
        board: A list of lists of strings representing the chessboard.

    Returns:
        The number of pawns the white rook is attacking.
    """

    rook_row, rook_col = -1, -1
    for i in range(8):
        for j in range(8):
            if board[i][j] == 'R':
                rook_row, rook_col = i, j
                break
        if rook_row != -1:
            break

    attacked_pawns = 0

    # Check upwards
    for i in range(rook_row - 1, -1, -1):
        if board[i][rook_col] == 'p':
            attacked_pawns += 1
            break
        elif board[i][rook_col] != '.':
            break

    # Check downwards
    for i in range(rook_row + 1, 8):
        if board[i][rook_col] == 'p':
            attacked_pawns += 1
            break
        elif board[i][rook_col] != '.':
            break

    # Check leftwards
    for j in range(rook_col - 1, -1, -1):
        if board[rook_row][j] == 'p':
            attacked_pawns += 1
            break
        elif board[rook_row][j] != '.':
            break

    # Check rightwards
    for j in range(rook_col + 1, 8):
        if board[rook_row][j] == 'p':
            attacked_pawns += 1
            break
        elif board[rook_row][j] != '.':
            break

    return attacked_pawns