Number of Islands Variation

Given a 2-D grid consisting of '1's (land) and '0's (water), compute 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. Example: Input: 11110 11010 11000 00000 Output: 1 Input: 11000 11000 00100 00011 Output: 3 Constraints: m == grid.length n == grid[i].length 1 <= m, n <= 300 grid[i][j] is '0' or '1'. Example Input 11110 11010 11000 00000