CodeGym/Help with Java Tasks/some little help please..

Level 15

26.08.2020
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16comments

some little help please..

Question about the task

Resolved

All seems to be working, but last condition not matched. I think the problem is in my second loop, it seems not taking the last value of the list. But I couldn't fix it (writes a bug that it is out of the ArrayList index).

1. Create a list of numbers.
2. Use the keyboard to add 10 numbers to the list.
3. Display the length of the longest sequence of repeating numbers in the list.

Example for the list 2, 4, 4, 4, 8, 8, 4, 12, 12, 14:
3

The value is 3, because the longest sequence of repeating numbers is three fours.

Requirements:

The program must display a number on the screen.
The program should read values from the keyboard.
In the main method, declare an ArrayList variable with Integer elements and immediately initialize it.
The program should add 10 numbers to the collection in accordance with the conditions.
The program should display the length of the longest sequence of repeating numbers in the list.

package com.codegym.task.task08.task0812; import java.io.*; import java.util.ArrayList; /* Longest sequence */ public class Solution { public static void main(String[] args) throws IOException { //write your code here BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); ArrayList <Integer> list= new ArrayList <Integer>(); ArrayList <Integer> sequenceSizes= new ArrayList <Integer>(); int count=1; for(int k=0; k<10; k++) { int num=Integer.parseInt(reader.readLine()) ; list.add(num); } for(int i=0; i<9; i++) { int a=list.get(i); int b=list.get(i+1); if (a==b) count++; else{ sequenceSizes.add(count); count=1; } } int max; max=sequenceSizes.get(0); for(Integer g: sequenceSizes) if(g>max) max=g; System.out.println(max); }}

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hidden #10653879

Level 13

30 August 2020, 21:53

Your code fails to update the list in which you are collecting sequence lengths. This is because the else clause is not executed. You need to update the longest sequence outside the if/else clause. loop from 1 to the end { if current number is the same as previous number then increment count else reset count bestCount is max of count or bestCount }

anna

Level 15

31 August 2020, 13:25

I tried, now it seems like it printed the max sequence number but still last condition not matched, look: public class Solution { public static void main(String[] args) throws IOException { Scanner sc= new Scanner (System.in); ArrayList<Integer> list = new ArrayList<Integer>(); ArrayList<Integer> repeats= new ArrayList<Integer>(); int max=0; int count=0; for (int i=0; i<10 ;i++) { list.add(sc.nextInt()); } for (int j=9; j>0 ;j--) { if (list.get(j)==list.get(j-1)) { count++; } else{ count=1; } repeats.add(count); } for(int k:repeats) { if(k>max) max=k; } System.out.println(max); } }

Misiu

Level 41 , Gdansk, Poland

31 August 2020, 14:46

1, 1, 2, 2, 3, 3, 4, 4, 4, 4 Output is 3. You are counting pairs. So: max of repeating numbers = count of pairs ... (and what else?)

anna

Level 15

31 August 2020, 16:26

it doesnt count pairs. the bug is that one of the loops didnt take the last number in, and every time the largest sequence was at the end it shows "result-1". So i found that bug, int count should be equal to 1 at the beginning and all the same. i ran this code with only changing: int count = 1; and still the task is not solved.. I really tried so many different inputs now. but it doesnt verify it...

Misiu

Level 41 , Gdansk, Poland

31 August 2020, 16:37

Last sequence has count = 0 at start of looping. Change it to: count = ... at the beginning of your code.

anna

Level 15

31 August 2020, 16:56

yeah, i got it thanks , but last condition is not verifying yet.. i tried it with all outputs, and all outputs worked.... I am feeling thrustreated, maybe i should type it again in the task? int max=0; int count=1; //all the rest as it was.

Misiu

Level 41 , Gdansk, Poland

31 August 2020, 19:40

Use: int max=1;

hidden #10653879

Level 13

31 August 2020, 20:16

Your code seems to be working fine. I don't know why it would not pass testing. I can't run it on the site anymore because the task is completed.

Misiu

Level 41 , Gdansk, Poland

31 August 2020, 21:41

Not working if there is no sequence longer then 1 (no sequences >= 2). Then max =0. Should be 1.

anna

Level 15

1 September 2020, 04:21

I tried also with max=1, the programm work the same both with max=0 and max=1. I am really batheled: This task is still not verifying... (And both values of max work and turn the right results).

anna

Level 15

1 September 2020, 04:54

I ran this code also on other decoders with all possible test inputs, I am sure the answer is 100% correct.. but when i ran it here it doesnt verify.. Maybe i missed something..? public class Solution { public static void main(String[] args) throws IOException { Scanner sc= new Scanner (System.in); ArrayList<Integer> list = new ArrayList<Integer>(); ArrayList<Integer> repeats= new ArrayList<Integer>(); int max=0; int count=1; for (int i=0; i<10 ;i++) { list.add(sc.nextInt()); } for (int j=9; j>0 ;j--) { if (list.get(j)==list.get(j-1)) { count++; } else{ count=1; } repeats.add(count); } for(int k:repeats) { if(k>max) max=k; } System.out.println(max); } }

Misiu

Level 41 , Gdansk, Poland

1 September 2020, 11:01

max must be 1. 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 must give 1. If max = 0 your code gives 0. Try: - don't use "repeats" list - move lines 43, 44 (old code) under count++ (in new code)

anna

Level 15

16 September 2020, 06:14

I puted this task aside for awhile, now solved it. thanks a lot! This is how I eventually rewrote this: //created a list with 10 numbers.. int max=0; int count=1; for(int i=1; i<10; i++){ if(list.get(i-1).equals(list.get(i))) count++; else count=1; if (count>max) max=count; } System.out.println(max);

Misiu

Level 41 , Gdansk, Poland

16 September 2020, 08:14

Nice to hear :)

dhanush

Level 30 , Chennai, India

26 August 2020, 12:02

Actually if a number interfered between the counting numbers means after the interfered number it stops counting and returns the result. For example if you entered a 5 numbers ->3 ->4 ->3 ->3 ->3 the actual output is 4 but your program returns 1.

Misiu

Level 41 , Gdansk, Poland

26 August 2020, 11:47

Not working if the longest sequence is at the end of the numbers.