0052-n-queens-ii.adoc

52. N-Queens II

{leetcode}/problems/n-queens-ii/[LeetCode - N-Queens II^]

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.."]
]

解题分析

解题分析参考 N-Queens。

link:{sourcedir}/_0052_NQueensII.java[role=include]

link:{sourcedir}/_0052_NQueensII_2.java[role=include]

参考资料

1. 52. N 皇后 II - 官方题解

2. 52. N 皇后 II - DFS + 位运算剪枝  — 简洁，但是一脸懵逼。

3. 代码随想录」52. N皇后 II:【回溯法经典问题】详解