#757 · #1463 · Cherry Pickup II(摘樱桃 II)

Given a rows x cols grid of cherries, two robots start at (0, 0) and (0, cols-1). Each step both move down one row, to a column within one of their current column. Collect cherries, counting each cell once. Return the maximum collected. Constraints: 1 <= rows, cols <= 70, 0 <= grid[i][j] <= 100.