Count connected land components in a grid

You are given a 2D grid of characters where:

• '1' represents land
• '0' represents water

A group of land cells forms an island if they are connected 4-directionally (up, down, left, right). Determine the number of islands in the grid.

Input

• grid: an m x n matrix of characters ('0' or '1').

Output

• Return an integer: the number of islands.

Constraints

• 1 <= m, n <= 300
• grid[i][j] ∈ {'0','1'}

Notes

• Diagonal adjacency does not connect islands.
• You may modify the grid in-place if desired.

Count Islands

Examples

Example 1

Input: ([['1','1','0','0'], ['1','0','0','1'], ['0','0','1','1']],)
Output: 2

Explanation: Two regions.

Example 2

Input: ([[1, 1], [1, 1]],)
Output: 1

Explanation: One island.

Hints

1. Start with a direct data structure representation.
2. Handle edge cases before the main loop.