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N Queens

Detailed guide and Python implementation for the 'N Queens' problem.

Problem Statement

Medium

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

Given an integer n, return all distinct solutions to the n-queens puzzle. You may return the answer in any order.

Each solution contains a distinct board configuration of the n-queens' placement, where 'Q' and '.' both indicate a queen and an empty space, respectively.

Implement a function solveNQueens(n: int) -> list.

Constraints
  • 1 <= n <= 9

Examples

Example 1
Input
4
Output
[[".Q..","...Q","Q...","..Q."],["..Q.","Q...",".Q..","...Q"]]
Explanation

There are exactly 2 distinct solutions to the 4-queens puzzle.

Example 2
Input
1
Output
[["Q"]]
Explanation

A single queen on a 1x1 board is the only solution.

Need a Hint?
Consider using Backtracking-specific data structures like sets or heaps.
Edge Cases to Watch
  • Empty input structures
  • Single element inputs
  • Large numerical bounds

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