Java Programming Help?

Question

A king once decided to grant amnesty to some of his prisoners due to lack of jail space rather than build a new prison.  He instructed his jailer to carryout the following procedure to determine which prisoners were to be set free.  The jailer was to first unlock each of the 1000 cells.  Then starting with the 2nd cell (number 2), he turned the key in every 2nd cell.  Then starting with the 3rd cell he turned the key in every 3rd cell; then starting the 4th, he turned the key in every 4th cell, etc.  Each turn of the key either locked or unlocked the cell door.  When he was completely done those with the unlocked doors could leave.  Who were the lucky ones?

deonejuan · Accepted Answer

import java.util.Arrays;


public class OneThousandJailCells {

    static final int HOOSEGOWS = 1000;
    static boolean[] locks = new boolean[HOOSEGOWS];

    public static void main(String[] args) {

        Arrays.fill(locks, true); // jailer keeps them locked
        int[] skipees = {2, 3, 4};
        Arrays.fill(locks, false); // they are all unlocked on holiday

        for (int i = 0; i < skipees.length; i++) {
            System.out.println("Jailer pass no " + (i + 1) + ", skip every " + skipees[i]);
            jailerWork(skipees[i]);


        }
        System.out.println("&#92;n&#92;nthe lucky ones are:::::::::::::");
        int luckies = 0;
        for (int i = 0; i < locks.length; i++) {
            if( !locks[i]) {
                System.out.printf("Cell no %3d unlocked%n", i+1);
                luckies ++;
            }

        }
        System.out.printf("Unlocked cells %d%n",luckies);
    }

    static private void jailerWork(int start) {
        for (int i = start; i < locks.length; i++) {
            locks[i - 1] = !locks[i - 1];
            i += start;
        }
        int t = inventory(locks);
        System.out.println("+===============" + t + " unlocked cells&#92;n");

    }

    static private int inventory(boolean[] l) {
        int totals = l.length;
        for (int i = 0; i < l.length; i++) {
            if (l[i]) {
                System.out.printf("Hoosegow No: %3d locked%n", i + 1);
                totals--;
            }
        }
        return totals;
    }
}

Trending News

Java Programming Help?

1 Answer