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sudoku.py
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sudoku.py
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import math
# Function to check if a number can be placed in the Sudoku grid at a particular position
def can_place(mat, i, j, n, no):
# Checking if the number already exists in the same row or column
for x in range(n):
if mat[x][j] == no or mat[i][x] == no:
return False
# Determining the starting index of the current sub-grid
rn = int(math.sqrt(n))
sx = (i // rn) * rn
sy = (j // rn) * rn
# Checking if the number already exists in the sub-grid
for x in range(sx, sx + rn):
for y in range(sy, sy + rn):
if mat[x][y] == no:
return False
return True
# Function to solve the Sudoku puzzle
def solve_sudoku(mat, i, j, n):
# Base case: If we have reached the last row, print the Sudoku solution
if i == n:
for x in range(n):
for y in range(n):
print(mat[x][y], end=" ")
print()
return True # Return True to indicate a solution is found
# If we have reached the last column, move to the next row
if j == n:
return solve_sudoku(mat, i + 1, 0, n)
# If the current cell already contains a number, move to the next column
if mat[i][j] != 0:
return solve_sudoku(mat, i, j + 1, n)
# Try placing numbers from 1 to n in the current empty cell
for no in range(1, n + 1):
if can_place(mat, i, j, n, no):
mat[i][j] = no # Place the number in the current cell
# Recursively solve the Sudoku puzzle for the next cell
could = solve_sudoku(mat, i, j + 1, n)
if could:
return True # Return True if a solution is found
# If no number can be placed in the current cell, backtrack
mat[i][j] = 0
return False
if __name__ == "__main__":
mat = [[0] * 9 for _ in range(9)]
n = int(input())
# Input the Sudoku grid
for i in range(n):
mat[i] = list(map(int, input().split()))
solve_sudoku(mat, 0, 0, n) # Solve the Sudoku puzzle