Count islands in a binary grid

## Problem You are given an `m x n` grid of characters where each cell is either `'1'` (land) or `'0'` (water). An **island** is formed by connecting adjacent land cells **horizontally or vertically** (not diagonally). The grid edges are surrounded by water. Return the **number of islands** in the grid. ## Input - `grid`: a 2D array/list of characters `'0'` and `'1'` ## Output - An integer: the number of islands ## Constraints - `1 <= m, n <= 300` - `grid[i][j] ∈ {'0','1'}` ## Example Input: ``` [ ['1','1','0','0','0'], ['1','1','0','0','0'], ['0','0','1','0','0'], ['0','0','0','1','1'] ] ``` Output: ``` 3 ``` Explanation: There are three disconnected land components.