Example 1:
Input: grid = [[".",".",".","."],[".","#","#","."],[".","#",".","."],[".",".",".","."]], start = [0,0], end = [2,3]
Output: true
Explanation:
Example 2:
Input: grid = [[".",".",".","."],["#","#","#","#"],[".",".",".","."]], start = [0,0], end = [2,3]
Output: false
Explanation:
Example 3:
Input: grid = [[".",".","."]], start = [0,1], end = [0,1]
Output: true
Explanation:
You are given a 2D grid of characters and two coordinates start and end. The player begins at start and may move one step at a time in any of the four orthogonal directions (up, down, left, right). Each cell is one of:
'.' — an empty cell the player can stand on.'#' — an obstacle. The player cannot enter this cell.Return true if the player can reach end from start, otherwise false.
start and end are each given as a length-2 array [row, col].
This was reported from a Roblox phone screen (February 2026). The interviewer asked for a DFS solution.
A valid path is (0,0) -> (1,0) -> (2,0) -> (3,0) -> (3,1) -> (3,2) -> (3,3) -> (2,3). Walking along the top row to (0,3) and then down also works.
A wall of obstacles in row 1 separates the top row from the bottom row, so no path exists.
Start equals end and the cell is not an obstacle.
1 <= grid.length, grid[i].length <= 100grid[i][j] is '.' or '#'.start.length == end.length == 20 <= start[0], end[0] < grid.length0 <= start[1], end[1] < grid[0].length