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 the number of distinct solutions to the n-queens puzzle.
Example:
Input: 4
Output: 2
Explanation: There are two distinct solutions to the 4-queens puzzle as shown below.
[
[".Q..", // Solution 1
"...Q",
"Q...",
"..Q."],
["..Q.", // Solution 2
"Q...",
"...Q",
".Q.."]
]
给定一个整数 n,返回 n 皇后不同的解决方案的数量。
- 这一题是第 51 题的加强版,在第 51 题的基础上累加记录解的个数即可。
- 这一题也可以暴力打表法,时间复杂度为 O(1)。