Count Islands in Grid

Problem Statement

You are given a 2D grid consisting of characters '1' representing land and '0' representing water. Your task is to determine how many distinct islands exist in the grid. An island is defined as a group of horizontally or vertically adjacent lands surrounded by water. The edges of the grid are considered to be water.

Examples

Example 1:

Grid:
11100
11000
10011
00000

Number of islands: 2

Example 2:

Grid:
10100
10100
00010
01110

Number of islands: 4

Constraints

• Grid rows: 1 to 150
• Grid columns: 1 to 150
• Each cell is either '1' or '0'