Getting unknown error in SudokuSolver Backtracking problem - recursion

Question

I was trying a Backtracking problem (SudokuSolver) I am getting an error which no-one could resolve or even understand. Hence I am seeking help here.
The problem is as follows:
And the main function/part of my code is:
Here my removerow, removecol and removebox functions are removing the numbers which have already occurred in that row, column and sub-box of 3x3 respectively.
The error I am getting is very long that is:
Can someone please help me with this? I'm stuck at it since 2 days. Ready to provide further clarification if needed.
Please find the entire code here: link

Answer 1

I have created a test class, to try understand what your functions are doing - or rather, to make sure they do what I think they do...
import unittest
from Otter.Help_Parth.entire_code import tellbox
from Otter.Help_Parth.entire_code import removerow
from Otter.Help_Parth.entire_code import removecol
from Otter.Help_Parth.entire_code import removebox
class MyTestCase(unittest.TestCase):
def test_tellbox(self):
""" Put each of the 81 x,y combination to tellbox
and retrieve the 81 corresponding box-numbers
assert that the numbers are as expected. """
lst_results = list()
for i in range(9):
for j in range(9):
lst_results.append(tellbox(i, j))
self.assertEqual(lst_results, [0, 0, 0, 3, 3, 3, 6, 6, 6, 0, 0, 0, 3, 3, 3, 6, 6, 6, 0, 0, 0, 3, 3, 3, 6, 6, 6, 1, 1, 1, 4, 4, 4, 7, 7, 7, 1, 1, 1, 4, 4, 4, 7, 7, 7, 1, 1, 1, 4, 4, 4, 7, 7, 7, 2, 2, 2, 5, 5, 5, 8, 8, 8, 2, 2, 2, 5, 5, 5, 8, 8, 8, 2, 2, 2, 5, 5, 5, 8, 8, 8])
def test_removerow(self):
""" Given a partly filled board, a list and an x,y coordinate
try call removerow() and assert that the returned list are as expected. """
board = [[1, 2, 3, 4, 5, 6, 7, 8, 9],
[4, 5, 6, 7, 8, 9, 1, 2, 3],
[7, 8, 9, 1, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0]]
l = [1, 2, 3, 4, 5, 6, 7, 8, 9]
x, y = 2, 4
res = removerow(l, board, x, y)
self.assertEqual([2, 3, 4, 5, 6], res)
def test_removecol(self):
""" Given a partly filled board, a list and an x,y coordinate
try call removecol() and assert that the returned list are as expected. """
board = [[1, 2, 3, 4, 5, 6, 7, 8, 9],
[4, 5, 6, 7, 8, 9, 1, 2, 3],
[7, 8, 9, 1, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0]]
l = [1, 2, 3, 4, 5, 6, 7, 8, 9]
x, y = 2, 4
res = removecol(l, board, x, y)
self.assertEqual([1, 2, 3, 4, 6, 7, 9], res)
def test_removebox(self):
""" Given a partly filled board, a list and an x,y coordinate
try call removebox() and assert that the returned list are as expected. """
board = [[1, 2, 3, 4, 5, 6, 7, 8, 9],
[4, 5, 6, 7, 8, 9, 1, 2, 3],
[7, 8, 9, 1, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 0, 0, 0]]
l = [1, 2, 3, 4, 5, 6, 7, 8, 9]
x, y = 2, 4
bno = tellbox(x, y)
res = removebox(l, board, x, y, bno)
self.assertEqual([2, 3], res)
if __name__ == '__main__':
unittest.main()
It all goes quite well, until removebox().
If you can read and understand my test_removebox(self) Are you kind to confirm that, under the given circumstances, it should in fact return [2, 3]?
Otherwise, please tell what it should return, and why?
When I run the test class, it returns the following:
NB: To be able to run the test class against your code, you need to change it like this:
if __name__ == '__main__':
board = [[ int(ele) for ele in input().split() ] for i in range(9)]
ans=solveSudoku(board,0,0)
if ans:
print('true')
else:
print('false')

Answer 2

Both your code-sample and the output seems incomplete.
We don't know your variables, so I assume 'board' is a list of 81 integers, but what is the mysterious (and newer used) boxl?
And why would you set board[x][y] = 0 (in the line with the comment), when you have just gone through the trouble of setting it = ele?
We would be able to help you better, if you provided the entire code, in a run-able form.

Answer 3

Sorry! I just realized that I answered to the wrong post!