Hard
Given a grid where each cell holds a number of cherries, two robots start at the top-left (0,0) and top-right (0, cols-1). Each robot moves down one row at a time to a diagonally-left, straight-down, or diagonally-right cell. When a robot passes a cell it collects its cherries; if both robots are on the same cell only one collection counts. Return the maximum cherries both robots can collect together after reaching the bottom row.
Input: grid = [[3,1,1],[2,5,1],[1,5,5],[2,1,1]] Output: 24
Input: grid = [[5]] Output: 5