Classic Island Problem on Grid (BFS/DFS)

Given a 2D grid grid consisting of 0/1, where 1 represents land and 0 represents water. Compute the number of islands in the grid. An island is defined as a connected component of lands (1) connected via 4-directional adjacency (up, down, left, right). Cells outside the grid are water. Input The first line contains two integers m n (rows and columns). The next m lines describe the grid (either as a string of length n or n space-separated digits). Output Print one integer: the number of islands. Constraints 1 <= m, n <= 2000 (typical interview scale; avoid recursion depth issues; iterative BFS/DFS recommended) 4-directional adjacency only Example Input grid: 11000 11000 00100 00011 Output: 3 Example Input 4 5 11000 11000 00100 00011 Output 3