Word Search with Modifications

Given a 2D board and a word, find if the word exists in the grid. The word can be constructed from letters of sequentially adjacent cells, where adjacent cells are those horizontally, vertically, or diagonally neighboring. Each cell can be reused. Cells outside the boundary of the grid are inaccessible. Implement a function exist(grid: List[List[str]], word: str) -> bool. Example: Input: grid = [['A','B','C','E'], ['S','F','C','S'], ['A','D','E','E']], word = "ABCCED" Output: true Constraints: 1 <= grid.length, grid[i].length <= 200 1 <= word.length <= min(grid.length * grid[i].length, 10^3) Example Input grid = [['A','B','C','E'],['S','F','C','S'],['A','D','E','E']] word = "ABCCED"