Leetcode•Feb 21, 2026

Available Captures for Rook

Hazrat Ali

Leetcode

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.

 

Solution

var numRookCaptures = function(board) {
    let rookRow = -1;
    let rookCol = -1;


    for (let i = 0; i < 8; i++) {
        for (let j = 0; j < 8; j++) {
            if (board[i][j] === 'R') {
                rookRow = i;
                rookCol = j;
                break;
            }
        }
    }

    let captures = 0;

   
    const directions = [
        [-1, 0],  
        [1, 0],  
        [0, -1],  
        [0, 1]    
    ];

   
    for (let [dx, dy] of directions) {
        let x = rookRow + dx;
        let y = rookCol + dy;

        while (x >= 0 && x < 8 && y >= 0 && y < 8) {
            if (board[x][y] === 'B') break;
            if (board[x][y] === 'p') {
                captures++;
                break;  
            }
            x += dx;
            y += dy;
        }
    }

    return captures;
};

 

 

 

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