Count Number of Islands

You have a 2D grid map of '1's (land) and '0's (water). Your task is to count the number of islands. An island is surrounded by water and is formed by connecting adjacent lands horizontally or vertically. Assume all four edges of the grid are surrounded by water. Given a 2D binary grid map of m x n dimensions, compute the number of islands. Example: Input: 11110 11010 11000 00000 Output: 1 Input: 11000 11000 00100 00011 Output: 3 Example Input 11110 11010 11000 00000