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Sudoku Solver Implementation
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Sudoku Solver Implementation

HardPython

Problem

Code out a Sudoku puzzle solver.

Implement solve_sudoku(board), modifying the given 9x9 board in place and returning it. Each cell contains a digit string from "1" to "9", or "." for an empty cell. Return a completed valid Sudoku board. Inputs are guaranteed to have exactly one solution.

A valid solution contains each digit exactly once in every row, column, and 3x3 subgrid.

Constraints

  • board is a 9x9 list of lists
  • Each cell is "." or a string digit from "1" through "9"
  • The input has exactly one valid solution
  • The function must modify board in place and return the completed board

Function Signature

def solve_sudoku(board):
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