Leetcode 0999. Available Captures for Rook

Problem statement

https://leetcode.com/problems/available-captures-for-rook/

Solution

First we need to find rook. Then let us create column and row for rook where we remove all empty cells. Finally, we loook for Rp or pR substrings in these row and column.

Complexity

Time complexity is O(64), space is O(8).

Code

class Solution:
    def numRookCaptures(self, B):
        y, x = next((i, j) for j in range(8) for i in range(8) if B[i][j] == 'R')
        row = "".join(B[y][j] for j in range(8) if B[y][j] != ".")
        col = "".join(B[i][x] for i in range(8) if B[i][x] != ".")
        return sum(a in b for a in ('Rp', 'pR') for b in (row, col))