Problem: Solving Sudoku Using PuLP, Part II

Specifying the constraints

1. Each box can only have one value.

To ensure that each box has only one value, we can keep row and col constant and vary values from 1 to 9. The sum of the binary values should be equal to 1 since only one variable will be equal to 1 and others must be 0, like this:

(value = 1, row =1, col =1) + (value = 2, row =1, col =1) + (value = 3, row =1, col =1) + (value = 4, row =1, col =1) + (value = 5, row =1, col =1) + (value = 6, row =1, col =1) + (value = 7, row =1, col =1) +(value = 8, row =1, col =1) +(value = 9, row =1, col =1) == 1

We will need to perform this check for all different combinations of row and col.