#Grid Traversal

Given a 2D grid of characters and a target string, determine whether the string can be constructed from adjacent cells moving in four possible directions (up, down, left, right). Each cell can only be used once in the path.

Given a 2D grid of '1's (land) and '0's (water), return the number of islands present in the grid. An island is surrounded by water and is formed by connecting adjacent lands horizontally or vertically.