Leetcode-Py/N-Queens.py at master · SocialfiPanda/Leetcode-Py · GitHub

27 lines (23 loc) · 1.23 KB

class Solution:

def solveNQueens(self, n):

solutions = []

self.solveRecur(solutions, [], n, 0)

return solutions

def solveRecur(self, solutions, solution, n, row):

if row == n:

solutions.append(map(lambda x: '.' * x + "Q" + '.' * (n - x - 1), solution))

for i in range(n):

if i not in solution and reduce(lambda acc, j: abs(row - j) != abs(i - solution[j]) and acc, range(len(solution)), True):

self.solveRecur(solutions, solution + [i], n, row + 1)

# The alternative is to make one line reduce function a separate method. Either way is fine.

# def is_diagonally_legal(self, solution, n, row, col):

# for i in range(len(solution)):

# if abs(row - i) == abs(col - solution[i]):

# return False

# return True

# def solveNQueensRecur(self, solutions, solution, n, i):

# if i == n:

# solutions.append(map(lambda x: '.' * x + "Q" + '.' * (n - x - 1), solution))

# for j in range(n):

# if j not in solution and self.is_diagonally_legal(solution, n, i, j):

# self.solveNQueensRecur(solutions, solution + [j], n, i + 1)

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