Question

Problem 1.Write a program that prompts the user to enter the number of milliseconds and converts the milliseconds to a string hours:minutes:seconds. The program should use the convertMillismethod with the following header:

public static String convertMillis(long millis)

For example, convertMillis(5500) returns the string 0:0:5, convertMillis(100000) returns the string 0:1:40, andconvertMillis(555550000) returns the string154:19:10.

Problem 2. (Count occurrence of numbers)Write a program that reads integers between 1 and 100 and counts the occurrence of each (you should store the numbers in an array). Output should be in ascending order. Assume the input ends when the user enters a 0. Here is a sample run of the program:

Enter integers between 1 and 100 (enter 0 to stop): 2 5 6 5 4 3 23 43 2 0

2 occurs 2 times

3 occurs 1 time

4 occurs 1 time

5 occurs 2 times

6 occurs 1 time

23 occurs 1 time

43 occurs 1 time

Note that if the number occurs more than one time, the plural word “times” is used in the output.

Problem 3. (Print distinct numbers)Write a program that reads in ten numbers and displays the number of distinct numbers and the distinct numbers separated by one space (i.e. if a number appears multiple times, it is displayed only once). (Hint: Read a number and store it to an array if it is new. If the number is already in the array, ignore it.) After the input, the array contains the distinct numbers. Here is an example run of the program:

Enter ten numbers: 1 2 3 2 1 6 3 4 5 2

The number of distinct numbers is 6

The distinct numbers are: 1 2 3 6 4 5

Answer 1

Solution to Problem 1:

public class MilliToHrsMinsSecs {
    public static void main(String[] args) {
        System.out.println(convertMillis(5500));
        System.out.println(convertMillis(100000));
        System.out.println(convertMillis(555550000));
    }

    public static String convertMillis(long millis) {
        String result;
        long hrs = 0, mins = 0, secs = 0;


        while (millis != 0) {
            if (millis >= 3600000) {
                hrs = millis / 3600000;
                millis = millis - hrs * 3600000;
            } else if (millis >= 60000) {
                mins = millis / 60000;
                millis = millis - mins * 60000;
            } else {
                secs = millis / 1000;
                millis = 0;
            }
        }
        result = hrs + ":" + mins + ":" + secs;
        return result;
    }
}

Output:

Solution to Problem 2:

import java.util.*;

public class Occurrences {
    public static void main(String[] args) {
        int[] numbers = new int[200];
        int i = 0, n;
        Scanner in = new Scanner(System.in);
        System.out.print("Enter integers between 1 and 100 (enter 0 to stop):");
        int val;
        val = in.nextInt();
        while (val != 0) {
            numbers[i] = val;
            val = in.nextInt();
            i = i + 1;
        }
        n = i;
        TreeMap values = new TreeMap();
        for (i = 0; i < n; i++) {
            values.put(numbers[i], 0);
        }
        Object ob;
        for (i = 0; i < n; i++) {

            ob = values.get(numbers[i]);

            if (ob != null) {
                values.put(numbers[i], values.get(numbers[i]) + 1);
            }
        }
        Set set = values.entrySet();
        Iterator x = set.iterator();
        int a, b;
        while (x.hasNext()) {
            Map.Entry current = (Map.Entry) x.next();
            a = (int) current.getKey();
            b = (int) current.getValue();
            if (b == 1)
                System.out.println(a + " occurs 1 time");
            else
                System.out.println(a + " occurs " + b + " times");

        }


    }

}

Output:

Solution to Problem 3:

import java.util.Scanner;

public class PrintDistinct {
    public static void main(String[] args) {
        System.out.print("Enter ten numbers:");
        Scanner in = new Scanner(System.in);
        int i, distinctnumbers = 0, val;
        int[] distincts = new int[10];
        for (i = 0; i < 10; i++) {
            val = in.nextInt();
            if (!isThere(distincts, distinctnumbers, val)) {
                distincts[distinctnumbers] = val;
                distinctnumbers = distinctnumbers + 1;
            }
        }
        System.out.println("The number of distinct numbers is " + distinctnumbers);
        System.out.print("The distinct numbers are:");
        for (i = 0; i < distinctnumbers; i++)
            System.out.print(" " + distincts[i]);
    }

    public static boolean isThere(int[] distincts, int distinctnumbers, int val) {
        int i;

        for (i = 0; i < distinctnumbers; i++) {
            if (val == distincts[i])
                return true;
        }
        return false;

    }

}

Output: