程序检查我们是否可以在Python中获得N个皇后解决方案
假设我们有一个二进制矩阵，其中0表示空单元格，而1表示该单元格的国际象棋皇后。我们必须检查是否可以填充此板并获得有效的nqueen解决方案。众所周知，n个皇后难题要求将n个皇后放置在n×n棋盘上，以便没有两个国际象棋皇后可以互相攻击。
所以，如果输入像
那么输出将为True，因为一种解决方案是-
例
让我们看下面的实现以更好地理解-
class Solution:
def solve(self, board):
def isSafe(board, i, j):
for r in range(len(board)):
if r != i and board[r][j] == 1:
return False
r, c = i + 1, j + 1
while r < len(board) and c < len(board[0]):
if board[r][c] == 1:
return False
r += 1
c += 1
r, c = i + 1, j - 1
while r < len(board) and c >= 0:
if board[r][c] == 1:
return False
r += 1
c -= 1
r, c = i - 1, j + 1
while r >= 0 and c < len(board[0]):
if board[r][c] == 1:
return False
r -= 1
c += 1
r, c = i - 1, j - 1
while r >= 0 and c >= 0:
if board[r][c] == 1:
return False
r -= 1
c -= 1
return True
r = c = 0
stack = []
while r < len(board):
if 1 in board[r]:
r += 1
continue
else:
found = False
while c < len(board[0]):
if isSafe(board, r, c):
board[r][c] = 1
stack.append([r, c])
found = True
break
c += 1
if found:
c = 0
r += 1
else:
if not stack:
return False
m = stack.pop()
r, c = m[0], m[1] + 1
board[r][c - 1] = 0
return True
ob = Solution()
matrix = [
[1, 0, 0, 0, 0],
[0, 0, 0, 0, 0],
[0, 0, 0, 0, 1],
[0, 0, 0, 0, 0],
[0, 0, 0, 1, 0]
]
print(ob.solve(matrix))输入值
[ [1, 0, 0, 0, 0], [0, 0, 0, 0, 0], [0, 0, 0, 0, 1], [0, 0, 0, 0, 0], [0, 0, 0, 1, 0] ]输出结果
True