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Grokking the Coding Interview Patterns in Python

N-Queens II

Explore the N-Queens II problem to learn how to count distinct ways to place n queens on a chessboard so none attack each other. Understand backtracking strategies and implement solutions that meet coding interview constraints.

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Statement

Given an integer, n, representing the size of an n x n chessboard, return the number of distinct ways to place n queens so that no two queens attack each other. A queen can attack another queen if they are in the same row, column, or diagonal.

Constraints:

  • 1≤1 \leq n ≤9\leq 9

Examples

Understand the problem

Let’s take a moment to make sure you’ve correctly understood the problem. The quiz below helps you check if you’re solving the correct problem:

N-Queens

1.

What is the correct solution to the 1-Queens problem?

A.

0

B.

1

C.

2

D.

4

1 / 5

Figure it out!

We have a game for you to play. Rearrange the logical building blocks to develop a clearer understanding of how to solve this problem.

Sequence - Vertical
Drag and drop the cards to rearrange them in the correct sequence.
1
2
3
4
5

Try it yourself

Implement your solution in main.py in the following coding playground.

Python
usercode > main.py
def totalNQueens(n):



    # Replace this placeholder return statement with your code

    return -1
N-Queens II