Leetcode 3529. Count Cells in Overlapping Horizontal and Vertical Substrings

Count how many cells belong to at least one horizontal substring (left-to-right, wrapping from end of a row to the first column of the next row) and at least one vertical substring (top-to-bottom, wrapping from bottom of a column to the first row of the next column) that both equal the given pattern. The challenge is to efficiently find and intersect all matching horizontal and vertical occurrences in an m×n grid (m·n ≤ 1e5) under the specified wrap rules.