Sudoku

Sudoku Pseudocode:

I. Create Board
    A. Split the input string
        string.split("")
    B. Convert into an array
        [master array]
II. Find empty cell
    A. Find first "-" in master array
    B. Define the variable
        current index = index # this is our unique id number!
III. Collect Corresponding Filled Cells
    A. We want to know what row, what column, and what box the index lives in. Define the following methods to do this:
        1. get_row method: index / 9
        2. get_column method: index % 9
        3. get_box method: (column/3 + row/3) * 3
    B. We want to find the existing corresponding numbers, NOT "-"'s, in the row column & box of our index value
        1. get_row (index / 9) && != "-" ==> [an array of values != "-" in row]
        2. get_column (index % 9) && != "-" ==> [an array of values != "-" in column]
        3. get_box (box index) && != "-" ==> [an array of values != "-" in box]
        # Put the results of these three arrays together for next step
IV. Test if We Have a Unique Solution
    A. If it is unique, it will only have 1 value in the array after we grab the unique values
        if ([1..9] - existing_corresp_nums.unique).length == 1
            master array [current index] = ([1..9] - existing_corresp_nums.unique).first
*** A while loop is necessary to keep going back through steps II. - IV. so long as there are still "-"'s present in the master array.  Recommended to use in driver code while building the program and then adding into the program at end***