ex2: init

assignment2/sudoku.py

@@ -0,0 +1,72 @@
+# Sudoku problems.
+# The CSP.ac_3() and CSP.backtrack() methods need to be implemented
+
+from csp import CSP, alldiff
+
+
+def print_solution(solution):
+    """
+    Convert the representation of a Sudoku solution, as returned from
+    the method CSP.backtracking_search(), into a Sudoku board.
+    """
+    for row in range(width):
+        for col in range(width):
+            print(solution[f'X{row+1}{col+1}'], end=" ")
+            if col == 2 or col == 5:
+                print('|', end=" ")
+        print("")
+        if row == 2 or row == 5:
+            print('------+-------+------')
+
+
+# Choose Sudoku problem
+grid = open('sudoku_easy.txt').read().split()
+
+width = 9
+box_width = 3
+
+domains = {}
+for row in range(width):
+    for col in range(width):
+        if grid[row][col] == '0':
+            domains[f'X{row+1}{col+1}'] = set(range(1, 10))
+        else:
+            domains[f'X{row+1}{col+1}'] = {int(grid[row][col])}
+
+edges = []
+for row in range(width):
+    edges += alldiff([f'X{row+1}{col+1}' for col in range(width)])
+for col in range(width):
+    edges += alldiff([f'X{row+1}{col+1}' for row in range(width)])
+for box_row in range(box_width):
+    for box_col in range(box_width):
+        cells = []
+        edges += alldiff(
+            [
+                f'X{row+1}{col+1}' for row in range(box_row * box_width, (box_row + 1) * box_width)
+                for col in range(box_col * box_width, (box_col + 1) * box_width)
+            ]
+        )
+
+csp = CSP(
+    variables=[f'X{row+1}{col+1}' for row in range(width) for col in range(width)],
+    domains=domains,
+    edges=edges,
+)
+
+print(csp.ac_3())
+print_solution(csp.backtracking_search())
+
+# Expected output after implementing csp.ac_3() and csp.backtracking_search():
+# True
+# 7 8 4 | 9 3 2 | 1 5 6
+# 6 1 9 | 4 8 5 | 3 2 7
+# 2 3 5 | 1 7 6 | 4 8 9
+# ------+-------+------
+# 5 7 8 | 2 6 1 | 9 3 4
+# 3 4 1 | 8 9 7 | 5 6 2
+# 9 2 6 | 5 4 3 | 8 7 1
+# ------+-------+------
+# 4 5 3 | 7 2 9 | 6 1 8
+# 8 6 2 | 3 1 4 | 7 9 5
+# 1 9 7 | 6 5 8 | 2 4 3