CodeGym/Help with Java Tasks/Can someone explain?

Level 11

Minsk

20.04.2019
1689views
12comments

Can someone explain?

Question about the task

Under discussion

Can you please explain, whi in IDE (idea) if 2 numbers equal - i see correct result, but check fails only for two exact numbers? I'v changed spaces between digits being printed - did not helped

Use the keyboard to enter three integers. Determine whether there is at least one pair of equal numbers among them.
If such a pair exists, display the numbers separated by a space.
If all three numbers are equal, then display all three.

Here are some examples:
a) if you enter the numbers
1
2
2
then we display
2 2

b) if you enter the numbers
2
2
2
then we display
2 2 2

Requirements:

The program should read the numbers from the keyboard.
The program should contain System.out.println() or System.out.print().
If two numbers are equal to each other, you must display them on the screen.
If all three numbers are equal, then display all three.
If there are no equal numbers, don't display anything.

package com.codegym.task.task04.task0417; /* Do we have a pair? */ import java.util.*; public class Solution { private static Map<Integer, Integer> hMap = new HashMap<>(); public static void main(String[] args) throws Exception { Scanner scanner = new Scanner(System.in); int val = 0; int total = 3; for (int i = 0; i < total; i++) { val = scanner.nextInt(); hMap.put(val, hMap.containsKey(val) ? hMap.get(val) + 1 : 1); } hMap.entrySet().stream().filter(en -> en.getValue() > 1).forEach(e -> printDuplicates(e.getKey(), e.getValue())); } private static void printDuplicates(int key, int count) { for (int i = 0; i < count; i++) { System.out.print(key + " "); } } }

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Connor

Level 8 , Boston, United States

21 April 2019, 21:51

I was going to try and help but I have no understanding of how to utilize maps lists arrays and the like. Could you explain those to me? Or are they covered thoroughly in a future chapter?

MixanJ

Level 11 , Minsk, Belarus

16 May 2019, 19:18

Hmm. I do not know in which chapter maps explained. But they should.

Guadalupe Gagnon

Level 37 , Tampa, United States

20 April 2019, 14:43

Outputs have to be exact, including spaces. Your code has a space at the end of each output which is failing the task.

MixanJ

Level 11 , Minsk, Belarus

16 May 2019, 19:19

As you can see check for 3 digits passes. Even if whitespace at the end: '3 3 3 '.It was my first thought about whitespace at the end.

Guadalupe Gagnon

Level 37 , Tampa, United States

16 May 2019, 19:38

Try this:

private static void printDuplicates(int key, int count) {
   StringBuilder x = new StringBuilder(String.valueOf(key));
   for (int i = 1; i < count; i++)
      x.append(" "+ key);

   System.out.println(x);
}

Thomas

Level 12 , Scottsdale, United States

26 May 2019, 04:28

Hello G.G. I ran this is Intelli J --- no luck yet ... thoughts ? I would really like to understand a map method functional approach ... THX

Guadalupe Gagnon

Level 37 , Tampa, United States

26 May 2019, 06:58

I should have probably had the OP try removing the static variable and just using a local variable. Might pass that way. Codegym's tasks don't like the use of static variables for some reason. Might have passed like this:

public class Solution {


    public static void main(String[] args) throws Exception {
        Map<Integer, Integer> hMap = new HashMap<>();
        int[] uinput = {586,3,586};

        int val = 0;

        int total = 3;
        for (int i = 0; i < total; i++) {
            val = uinput[i];
            hMap.put(val, hMap.containsKey(val) ? hMap.get(val) + 1 : 1);
        }

        hMap.entrySet().stream().filter(en -> en.getValue() > 1).forEach(e -> printDuplicates(e.getKey(), e.getValue()));
    }

    private static void printDuplicates(int key, int count) {
        StringBuilder x = new StringBuilder(String.valueOf(key));
        for (int i = 1; i < count; i++)
            x.append(" "+ key);

        System.out.println(x);
    }

}

Steven Mcilhone

Level 17 , Belfast, United Kingdom

20 April 2019, 13:38

check if a and b equal eachother and c doesnt (a == b && a !=c) then print a and b, do this for a & c !b and b and c !a, then check if a == b && b==c

MixanJ

Level 11 , Minsk, Belarus

16 May 2019, 19:21

Yep. It works, but not greatest solution. What if we need 4 variables, 5 and more? Then our code will growing. I tried solution which can handle more than 3 variables in simple way.

Steven Mcilhone

Level 17 , Belfast, United Kingdom

16 May 2019, 22:31

well for now this is fine, later you could add the inputs to an arraylist, then loop though the arraylist, could be 1000's of numbers and print the answer

Sela

Level 20 , Poland

21 June 2020, 04:35

the problem is that the examples given in the task (and a word "pair") suggest that only ordered numbers are significant, like: 1 2 2 or 2 2 2 but in the text there is no a word of ordering. the numbers just have to be equal. so if you put 2 1 2 output should also be 2 2 notice that the space after last digit does not matter

Sela

Level 20 , Poland

21 June 2020, 12:35

for longer arrays - for example 5 numbers: 2 1 2 4 5 your output should be: 2 2 another example: input: 3 3 0 2 2 output: 3 3 2 2 if you write code to be able to output the results like in above examples, then the code passes the check