下面是一个使用Python编写的数独求解程序。这个程序使用了回溯算法来找到数独的解决方案。
//```python
def print_board(board):
for row in board:
print(" ".join(str(num) for num in row))
def find_empty_location(board):
for i in range(9):
for j in range(9):
if board[j] == 0:
return (i, j)
return None
def is_safe(board, row, col, num):
# Check if 'num' is not already placed in current row, current column and current 3x3 box
for x in range(9):
if board[row][x] == num or board[x][col] == num:
return False
start_row, start_col = 3 * (row // 3), 3 * (col // 3)
for i in range(start_row, start_row + 3):
for j in range(start_col, start_col + 3):
if board[j] == num:
return False
return True
def solve_sudoku(board):
empty_loc = find_empty_location(board)
if not empty_loc:
return True # Puzzle solved
row, col = empty_loc
for num in range(1, 10):
if is_safe(board, row, col, num):
board[row][col] = num
if solve_sudoku(board):
return True
board[row][col] = 0 # Backtrack
return False
if __name__ == "__main__":
board = [
[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]
]
if solve_sudoku(board):
print_board(board)
else:
print("No solution exists")
//```
这个程序首先定义了一个打印数独棋盘的函数`print_board`,一个查找空白位置的函数`find_empty_location`,一个检查数字是否可以放在某个位置的函数`is_safe`,以及主要的解决数独的函数`solve_sudoku`。最后在主函数中初始化一个数独棋盘并调用`solve_sudoku`函数尝试解决它。如果找到了解决方案,它会打印出来;如果没有解决方案,它会输出"No solution exists"。
纠正数独中的错误,给出正确答案:
数独问题的正确答案如下:
5 3 4 | 6 7 8 | 9 1 2
6 7 2 | 1 9 5 | 3 4 8
1 9 8 | 3 4 2 | 5 6 7
------+------+------
8 5 9 | 7 6 1 | 4 2 3
4 2 6 | 8 5 3 | 7 9 1
7 1 3 | 9 2 4 | 8 5 6
------+------+------
9 6 1 | 5 3 7 | 2 8 4
2 8 7 | 4 1 9 | 6 3 5
3 4 5 | 2 8 6 | 1 7 9
请注意,此解答基于标准数独规则,即每行、每列及每个3x3宫格内的数字从1到9各出现一次。
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