Need to implement set and get operations.
Be aware that one cell may depend on other cells, e.g. cells[1, 2] = cells[1, 1] + cell[1, 3] * 2
Design excel table

Could you give more details in the description and an example?
For example, it is not clear how the inputs are given. How is the spreadsheet represented? A 2d array of cells? Each cell contains a string?
Input:
[ ["100", "A2*3"], ["B2+A1", "200"] ]
Output:
[ ["100", "900"], ["300", "200"] ]
Is it like the above? And what about circular reference? What should the output be?