Create 2. Backward with Forward Checking.py

Author: MennahtullahMabrouk

CSP Sudoku/2. Backward with Forward Checking.py

@@ -0,0 +1,113 @@
+import tkinter as tk
+import time
+from itertools import product
+
+def is_valid_move(puzzle, row, col, num):
+    if num in puzzle[row] or num in [puzzle[i][col] for i in range(9)]:
+        return False
+
+    subgrid_row, subgrid_col = 3 * (row // 3), 3 * (col // 3)
+    for i in range(subgrid_row, subgrid_row + 3):
+        for j in range(subgrid_col, subgrid_col + 3):
+            if puzzle[i][j] == num:
+                return False
+
+    return True
+
+def solve_sudoku_csp(puzzle):
+    def is_valid_move_with_forward_checking(puzzle, row, col, num):
+        if num in puzzle[row] or num in [puzzle[i][col] for i in range(9)]:
+            return False
+
+        subgrid_row, subgrid_col = 3 * (row // 3), 3 * (col // 3)
+        for i in range(subgrid_row, subgrid_row + 3):
+            for j in range(subgrid_col, subgrid_col + 3):
+                if puzzle[i][j] == num:
+                    return False
+
+        # Check for forward checking in the row
+        if any(puzzle[row][c] == num for c in range(9) if c != col and puzzle[row][c] == 0):
+            return False
+
+        # Check for forward checking in the column
+        if any(puzzle[r][col] == num for r in range(9) if r != row and puzzle[r][col] == 0):
+            return False
+
+        return True
+
+    def solve(puzzle):
+        for row, col in product(range(9), repeat=2):
+            if puzzle[row][col] == 0:
+                for num in range(1, 10):
+                    if is_valid_move_with_forward_checking(puzzle, row, col, num):
+                        puzzle[row][col] = num
+                        set_puzzle(puzzle)
+                        app.update()
+                        time.sleep(0.1)  
+                        if solve(puzzle):
+                            return True
+                        puzzle[row][col] = 0
+                return False
+        return True
+
+    if solve(puzzle):
+        return puzzle
+    return None
+
+app = tk.Tk()
+app.title("CSP Sudoku Solver")
+
+sudoku_labels = [[0 for _ in range(9)] for _ in range(9)]
+
+for i in range(9):
+    for j in range(9):
+        label = tk.Label(app, width=4, height=2, relief="ridge", borderwidth=2)
+        label.grid(row=i, column=j, padx=5, pady=5)
+        label.config(font=("Arial", 16))
+        sudoku_labels[i][j] = label
+
+# Create bold borders for 3x3 subgrids
+for i in range(0, 9, 3):
+    for j in range(0, 9, 3):
+        for x in range(3):
+            for y in range(3):
+                label = sudoku_labels[i + x][j + y]
+                label.config(borderwidth=2 if x == 1 and y == 1 else 1)
+
+def set_puzzle(puzzle):
+    for i in range(9):
+        for j in range(9):
+            value = puzzle[i][j]
+            label = sudoku_labels[i][j]
+            if value == 0:
+                label.config(text="", bg="white")
+            else:
+                label.config(text=str(value), bg="lightgray")
+
+def clear_puzzle():
+    for i in range(9):
+        for j in range(9):
+            label = sudoku_labels[i][j]
+            label.config(text="", bg="white")
+
+clear_button = tk.Button(app, text="Clear", command=clear_puzzle)
+clear_button.grid(row=10, column=4, padx=5, pady=10)
+
+solve_button = tk.Button(app, text="Solve CSP", command=lambda: solve_sudoku_csp(puzzle))
+solve_button.grid(row=10, column=3, padx=5, pady=10)
+
+puzzle = [
+    [5, 3, 0, 0, 7, 0, 0, 0, 0],
+    [6, 0, 0, 1, 9, 5, 0, 0, 0],
+    [0, 9, 8, 0, 0, 0, 0, 6, 0],
+    [8, 0, 0, 0, 6, 0, 0, 0, 3],
+    [4, 0, 0, 8, 0, 3, 0, 0, 1],
+    [7, 0, 0, 0, 2, 0, 0, 0, 6],
+    [0, 6, 0, 0, 0, 0, 2, 8, 0],
+    [0, 0, 0, 4, 1, 9, 0, 0, 5],
+    [0, 0, 0, 0, 8, 0, 0, 7, 9]
+]
+
+set_puzzle(puzzle)
+
+app.mainloop()