N Kueen - HackerRank Code Sprint - Interviewstreet.com

NKueen.java

import java.util.ArrayList;
import java.util.Scanner;


public class NKueen {
	
	private static ArrayList<Integer> kueens = new ArrayList<Integer>();
	static int N = 0;
	
	public static void main (String args[]){
		Scanner in = new Scanner(System.in);
		
		//input
		N = in.nextInt();
		
		//loop through 
		generatePositions();
		
		//output positions
		outputKueenPositions();
	}

	
	private static void outputKueenPositions() {
		System.out.println(N);
		for(int i = 0; i < kueens.size();i++){
			if(i == kueens.size() -1){
				System.out.print(kueens.get(i) + " ");
			}else{
				System.out.print(kueens.get(i) + " ");
			}
			
		}
	}

	

	private static void generatePositions() {
		boolean col1Empty = true;
		boolean col2Empty = true;
		int c = 3; //column number - start from column 3
		
		if(N <= 3){
			c = 1;
			kueens.add(c);
		}else{
			kueens.add(c);
			
			for(int r = 1; r < N;r++){
				if(c+3 <= N){
					c = c+3;
					kueens.add(c);
				}else{
					if(col1Empty){
						c = 1;
						col1Empty = false;
						kueens.add(c);
					}else if(col2Empty){
						c = 2;
						col2Empty = false;
						kueens.add(c);
					}else{
						c = (c+3) - N;
						kueens.add(c);
					}
					
				}
			}
		}
		
		
	}
}

If it makes you feel better, we didn't get it either. Write out the numbers row-by-row. What do you notice about them? You already mentioned a pattern; see if you can write it out. It's a simple formula. Hint (rot13): Vg vaibyirf n zbqhyhf. - Christian

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On Mon, Jul 23, 2012 at 5:08 PM, robbio87 < ***@***.*** > wrote: Yeah, it was a very basic attempt, I still haven't come up with any correct solution. The only pattern I could see was each queen was separated by 3 columns and 1 row, and no matter what N is, there will be 3 diagonal rows of Queens... I need more practice :D --- Reply to this email directly or view it on GitHub: https://gist.github.com/3163641