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Program.cs
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Program.cs
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using System;
namespace SudokuSolver
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine("Hello World!");
}
public void SolveSudoku(char[][] board)
{
var rowUsed = new bool[9][];
var colUsed = new bool[9][];
var sqrtUsed = new bool[9][];
for (int i = 0; i < 9; i++)
{
rowUsed[i] = new bool[9];
colUsed[i] = new bool[9];
sqrtUsed[i] = new bool[9];
}
for (int r = 0; r < 9; r++)
{
for (int c = 0; c < 9; c++)
{
if(board[r][c] == '.') continue;
int num = board[r][c] - '1';
int index = r / 3 * 3 + c / 3;
rowUsed[r][num] = true;
colUsed[c][num] = true;
sqrtUsed[index][num] = true;
}
}
DFS(board, rowUsed, colUsed, sqrtUsed);
}
private bool DFS(char[][] board, bool[][] rowUsed, bool[][] colUsed, bool[][] sqrtUsed)
{
for (int r = 0; r < 9; r++)
{
for (int c = 0; c < 9; c++)
{
if(board[r][c] != '.') continue;
for (int i = 0; i < 9; i++)
{
int index = r / 3 * 3 + c / 3;
if (rowUsed[r][i] || colUsed[c][i] || sqrtUsed[index][i]) continue;
rowUsed[r][i] = true;
colUsed[c][i] = true;
sqrtUsed[index][i] = true;
board[r][c] = (char) (i + '1');
if (DFS(board, rowUsed, colUsed, sqrtUsed))
return true;
rowUsed[r][i] = false;
colUsed[c][i] = false;
sqrtUsed[index][i] = false;
board[r][c] = '.';
}
return false;
}
}
return true;
}
}
}