package main
import (
"fmt"
"os"
)
const boardSize = 9
func main() {
// Read command-line input as strings representing rows of the Sudoku grid
boardStrings := os.Args[1:]
// Check if the number of input rows matches the board size
if len(boardStrings) != boardSize {
fmt.Println("Error")
return
}
// Create a 2D rune slice to represent the Sudoku board
board := make([][]rune, boardSize)
for i, s := range boardStrings {
// Check if the length of each row matches the board size
if len(s) != boardSize {
fmt.Println("Error")
return
}
board[i] = []rune(s)
}
// Validate the initial configuration of the Sudoku board
if !isValidSudoku(board) {
fmt.Println("Error")
return
}
// Solve the Sudoku board using backtracking algorithm
if !solveBoard(board) {
fmt.Println("Error")
return
}
// Print the solved Sudoku board
for _, row := range board {
for _, num := range row {
fmt.Printf("%c ", num)
}
fmt.Println()
}
}
// Function to validate the entire Sudoku board
func isValidSudoku(board [][]rune) bool {
for i := 0; i < boardSize; i++ {
// Check each row, column, and 3x3 subgrid for validity
if !isValidRow(board, i) || !isValidColumn(board, i) || !isValidSubgrid(board, i/3*3, i%3*3) {
return false
}
}
return true
}
// Function to validate a row in the Sudoku board
func isValidRow(board [][]rune, row int) bool {
seen := make(map[rune]bool)
for _, num := range board[row] {
if num != '.' && seen[num] {
return false
}
seen[num] = true
}
return true
}
// Function to validate a column in the Sudoku board
func isValidColumn(board [][]rune, col int) bool {
seen := make(map[rune]bool)
for i := 0; i < boardSize; i++ {
num := board[i][col]
if num != '.' && seen[num] {
return false
}
seen[num] = true
}
return true
}
// Function to validate a 3x3 subgrid in the Sudoku board
func isValidSubgrid(board [][]rune, startRow, startCol int) bool {
seen := make(map[rune]bool)
for i := 0; i < 3; i++ {
for j := 0; j < 3; j++ {
num := board[startRow+i][startCol+j]
if num != '.' && seen[num] {
return false
}
seen[num] = true
}
}
return true
}
// Function to solve the Sudoku board using backtracking
func solveBoard(board [][]rune) bool {
// Find the next empty cell in the board
row, col := findEmptyCell(board)
if row == -1 {
return true // Entire board is filled, solution found
}
for digit := '1'; digit <= '9'; digit++ {
// Try placing each valid digit in the empty cell
if isValidPlacement(board, row, col, digit) {
board[row][col] = digit
if solveBoard(board) {
return true // Recursive solution found
}
board[row][col] = '.' // Backtrack
}
}
return false // No valid digit found, backtrack
}
// Function to validate placing a digit in a specific cell
func isValidPlacement(board [][]rune, row, col int, digit rune) bool {
for i := 0; i < boardSize; i++ {
// Check the row, column, and 3x3 subgrid for conflicts
if board[row][i] == digit || board[i][col] == digit || board[row/3*3+i/3][col/3*3+i%3] == digit {
return false
}
}
return true
}
// Function to find the next empty cell in the Sudoku board
func findEmptyCell(board [][]rune) (int, int) {
for i, r := range board {
for j, c := range r {
if c == '.' {
return i, j // Return coordinates of the empty cell
}
}
}
return -1, -1 // No empty cell found
}