51. N-Queensr[H]

https://leetcode.com/problems/n-queens/

Description

The n-queens puzzle is the problem of placing n queens on an n×n chessboard such that no two queens attack each other.

img

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:

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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.

Solution

1

52. N-Queens II[H]

https://leetcode.com/problems/n-queens-ii/

Description

The n-queens puzzle is the problem of placing n queens on an n×n chessboard such that no two queens attack each other.

img

Given an integer n, return the number of distinct solutions to the n-queens puzzle.

Example:

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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.."]

Solution