Python 无法使用回溯获取数独解算器的输出
我开始使用回溯和递归来研究数独解算器。我无法打印已解决的数独。我已经测试了Python 无法使用回溯获取数独解算器的输出,python,python-3.x,recursion,sudoku,recursive-backtracking,Python,Python 3.x,Recursion,Sudoku,Recursive Backtracking,我开始使用回溯和递归来研究数独解算器。我无法打印已解决的数独。我已经测试了可能的(y,x,n)方法,它很有效。程序以结束,进程以退出代码0结束,但不打印已解决的数独难题。我正在使用python 3.7和PyCharm Community Edition 2020.1.3作为我的IDE import numpy as np grid = [[5, 3, 0, 0, 7, 0, 0, 0, 0], [6, 0, 0, 1, 5, 9, 0, 0, 0], [0, 9
可能的(y,x,n)
方法,它很有效。程序以结束,进程以退出代码0结束,但不打印已解决的数独难题。我正在使用python 3.7和PyCharm Community Edition 2020.1.3作为我的IDE
import numpy as np
grid = [[5, 3, 0, 0, 7, 0, 0, 0, 0],
[6, 0, 0, 1, 5, 9, 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]]
def possible(y, x, n):
global grid
for i in range(9):
if grid[y][i] == n:
return False
for i in range(9):
if grid[x][i] == n:
return False
x0 = (x // 3) * 3
y0 = (y // 3) * 3
for i in range(3):
for j in range(3):
if grid[y0 + i][x0 + j] == n:
return False
return True
def solve():
global grid
for y in range(9):
for x in range(9):
if grid[y][x] == 0:
for n in range(1, 10):
if possible(y, x, n):
grid[y][x] = n
solve()
grid[y][x] = 0
return
print(np.matrix(grid))
if __name__ == "__main__":
solve()
我已经测试了可能的(y,x,n)方法,它是有效的
但它坏了:
if grid[x][i] == n:
应该是:
if grid[i][x] == n:
下一个问题是你试图解决的难题,它被破解了!第六列有两个9:
[., ., ., ., ., 0, ., ., .]
[., ., ., ., ., 9, ., ., .]
[., ., ., ., ., 0, ., ., .]
[., ., ., ., ., 0, ., ., .]
[., ., ., ., ., 3, ., ., .]
[., ., ., ., ., 0, ., ., .]
[., ., ., ., ., 0, ., ., .]
[., ., ., ., ., 9, ., ., .]
[., ., ., ., ., 0, ., ., .]
您可能希望向函数集添加一个谜题验证器。在我下面的例子中,我使用了一个不同的可以解决的难题,否则很难调试代码
最后,您的solve()
函数将得到授权。它不应该打印谜题,而是返回一个布尔值,指示它是否解决了谜题。这个结果然后用于回溯,并在最后确定该谜题是否可解
最后,请仔细阅读global
关键字,您没有正确使用它
import numpy as np
def possible(y, x, n):
for i in range(9):
if grid[y][i] == n:
return False
for i in range(9):
if grid[i][x] == n:
return False
x0 = (x // 3) * 3
y0 = (y // 3) * 3
for i in range(3):
for j in range(3):
if grid[y0 + i][x0 + j] == n:
return False
return True
def solve():
for y in range(9):
for x in range(9):
if grid[y][x] == 0:
for n in range(1, 10):
if possible(y, x, n):
grid[y][x] = n # tentatively try n
solved = solve()
if solved:
return True # solved recursively!
grid[y][x] = 0 # undo attempt at n
return False # no solution for this square
return True # no 0's to resolve, puzzle solved!
if __name__ == "__main__":
grid = [
[6, 5, 8, 0, 0, 0, 0, 7, 0],
[0, 7, 0, 0, 5, 0, 8, 0, 0],
[0, 3, 9, 0, 0, 0, 5, 4, 0],
[0, 0, 2, 6, 0, 5, 0, 0, 7],
[0, 6, 0, 9, 7, 4, 0, 0, 0],
[7, 0, 0, 3, 0, 0, 6, 0, 0],
[0, 4, 6, 0, 0, 0, 2, 5, 0],
[0, 0, 7, 0, 6, 0, 0, 0, 0],
[0, 0, 0, 0, 0, 0, 7, 6, 8]
]
if solve():
print(np.matrix(grid))
else:
print("No solution!")
输出
> python3 test.py
[[6 5 8 1 4 3 9 7 2]
[4 7 1 2 5 9 8 3 6]
[2 3 9 7 8 6 5 4 1]
[3 9 2 6 1 5 4 8 7]
[8 6 5 9 7 4 1 2 3]
[7 1 4 3 2 8 6 9 5]
[1 4 6 8 3 7 2 5 9]
[9 8 7 5 6 2 3 1 4]
[5 2 3 4 9 1 7 6 8]]
>
在solve()
函数中有一个早期的return
语句,这就是为什么行print(np.matrix(grid))
不运行的原因。