The n-queens puzzle is the problem of placing n queens on an n×n chessboard such that no two queens attack each other.
Given an integer n, return all distinct solutions to the n-queens puzzle.
Each solution contains a distinct board configuration of the n-queens' placement, where 'Q' and '.' both indicate a queen and an empty space respectively.
Example:
Input: 4 Output: [ [".Q..", // Solution 1 "...Q", "Q...", "..Q."],
["..Q.", // Solution 2 "Q...", "...Q", ".Q.."] ] Explanation: There exist two distinct solutions to the 4-queens puzzle as shown above.
My code:
class Solution:
def solveNQueens(self, n):
"""
:type n: int
:rtype: List[List[str]]
"""
self.n=n
self.result = []
self.DFS([],[],[])
return [ ["."*i + "Q" + "."*(n-i-1) for i in sol] for sol in self.result]
def DFS(self,queens, xy_dif, xy_sum):
p = len(queens)
if p==self.n:
self.result.append(queens)
return None
for q in range(self.n):
if q not in queens and p-q not in xy_dif and p+q not in xy_sum:
self.DFS(queens+[q], xy_dif+[p-q], xy_sum+[p+q]) Solution: https://leetcode.com/problems/n-queens/