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Author: Anshir08

sudoku.py

@@ -0,0 +1,81 @@
+def print_grid(arr):
+    for i in range(9):
+        for j in range(9):
+            print (arr[i][j], end = " ")
+        print()
+
+def find_empty_location(arr, l):
+    for row in range(9):
+        for col in range(9):
+            if arr[row][col] == 0:
+                l[0] = row
+                l[1] = col
+                return True
+    return False
+
+def used_in_row(arr, row, num):
+    for i in range(9):
+        if (arr[row][i] == num):
+            return True
+    return False
+
+def used_in_col(arr, col, num):
+    for i in range(9):
+        if (arr[i][col] == num):
+            return True
+    return False
+
+def used_in_box(arr, row, col, num):
+    for i in range(3):
+        for j in range(3):
+            if (arr[i + row][j + col] == num):
+                return True
+    return False
+
+def check_location_is_safe(arr, row, col, num):
+    return not used_in_row(arr, row, num) and not used_in_col(arr, col, num) and not used_in_box(arr, row - row % 3, col - col % 3, num)
+
+
+def solve_sudoku(arr):
+
+    l = [0, 0]
+
+    if (not find_empty_location(arr, l)):
+        return True
+    
+    row = l[0]
+    col = l[1]
+
+    for num in range(1, 10):
+
+        if (check_location_is_safe(arr, row, col, num)):
+            arr[row][col] = num
+
+            if (solve_sudoku(arr)):
+                return True
+
+            arr[row][col] = 0
+
+    return False
+
+
+if __name__=="__main__":
+     
+    # creating a 2D array for the grid
+    grid =[[0 for x in range(9)]for y in range(9)]
+     
+    grid =[[3, 0, 6, 5, 0, 8, 4, 0, 0],
+          [5, 2, 0, 0, 0, 0, 0, 0, 0],
+          [0, 8, 7, 0, 0, 0, 0, 3, 1],
+          [0, 0, 3, 0, 1, 0, 0, 8, 0],
+          [9, 0, 0, 8, 6, 3, 0, 0, 5],
+          [0, 5, 0, 0, 9, 0, 6, 0, 0],
+          [1, 3, 0, 0, 0, 0, 2, 5, 0],
+          [0, 0, 0, 0, 0, 0, 0, 7, 4],
+          [0, 0, 5, 2, 0, 6, 3, 0, 0]]
+     
+    
+    if(solve_sudoku(grid)):
+        print_grid(grid)
+    else:
+        print("No solution exists")