Let’s consider a scenario with an $(m \times n)$ 2D grid containing binary numbers, where '0' represents water and '1' represents land. If any '1' cells are connected to each other horizontally or vertically (not diagonally), they form an island. Your task is to return the total number of islands in the grid.

Constraints:

• $1 \leq$ grid.length $\leq 50$

• $1 \leq$ ...