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Arithmetic Progression in java

i'm just started to learn java yesterday. But, now i met difficulty to show the arithmetic progression like the display below:
1 2 2 2 3 3 3 3 3 4 4 4 4 4 4 4
From that example, i know that every odd numbers, the numbers increment. I've tried to make it, but the display just keep showing like this:
2 4 4 4 6 6 6 6 6 8 8 8 8 8 8 8 10 10 10 10 10 10 10 10 10
Here's my code:
for (int i = 0; i <= 10; i++) {
if (i % 2 == 0) {
for(int j = 1; j<i; j++){
System.out.print(i + " ");
}
}
}
And then, i want to take the last value of it. For example, if i have row = 3, it must be value = 2.
because :
row = 1 2 3 4 5 6 7 8 9 10
value = 1 2 2 2 3 3 3 3 3 4
Would you tell me, what line is exactly must be fix? Thank you

It's not about a line that is wrong, it's your approach that's a bit off. You could fix it in multiple ways. Easiest (but not most efficient) way is this:
for (int i = 0; i <= 10; i++) {
if (i % 2 == 0) {
for(int j = 1; j<i; j++){
System.out.print((i/2) + " ");
}
}
}
As you can see, only the output was changed and now it works. However, iterating over 11 numbers (0-10) when you only really care about 4-5 is not necessarily the best way to go here.
It also doesn't make your code easy to understand.
Here's an alternative.
int amount = 1;
for (int i = 1; i <= 5; i++) {
for (int j = 0; j < amount; j++) {
System.out.print(i + " ");
}
amount = amount + 2;
}
Here you can see that the outer for has been changed to only take the numbers we actually care about, which means we can remove the if completely.
We just have to somehow decide how many times we want to execute the print call, which is done with the amount variable.

Try this.
for (int i = 1, r = 1; i <= 4; ++i, r += 2)
System.out.print((i + " ").repeat(r));
You can calculate value from row with this method.
static int value(int row) {
return (int)Math.ceil(Math.sqrt(row));
}
So you can also do like this.
for (int row = 1; row <= 16; ++row)
System.out.print(value(row) + " ");
result:
1 2 2 2 3 3 3 3 3 4 4 4 4 4 4 4

Hey it's a representation of a sequence that grows by 2 every step.
i.e the first element is 1 which shows up one time.
the second element is 3 which shows up 3 times (2 2 2)
and so on and on..
so the code you need is:
int a = 1;
for(int i=1; i<=10;i++){
int j=1;
while(j<=a){
System.out.print(i);
j++;
}
a+=2;
}
printing the value in a wanted row:
Scanner in = new Scanner(System.in);
int rowU = in.nextInt(); // User inputs row
int row = 1; // a variable to keep track of the rows
int repeats = 1; // the number of times a value shoud appear
for(int value=1;value<=10;value++){
int j=1;
while(j<=repeats){
if(row==rowU) // if we got to the wanted row
System.out.println(value); // print the wanted value
j++;
row++;
}
repeats+=2;
}
There is a better, more efficient way to get the value of a wanted row:
int wanted_value = Math.ceil(Math.sqrt(wanted_row));
Thanks to #saka for bringing this one up!
Hope I helped :)

i % 2 == 0 means that the following code is only going to be executed, if i is even.
You could try removing the if, and change the second for to something like
int j = 0; j < 2 * i - 1; j++.

This code snippet will do the work
int n=4;
int printTimes=1;
for(int i=1;i<=n;i++)
{
for(int j=0;j<printTimes;j++)
System.out.print(i+" ");
printTimes+=2;
}
System.out.println();

Here is the example code.
int start = 1;
int end = 5;
int time = 1;
for (int i = start,j = time; i < end; i++,j+=2) {
for (int k = 0; k < j; k++) {
System.out.print(i+" ");
}
}

How do you print the sequence one 1, then two 2, three 3, ... n ns?

Write a program that prints a part of the sequence:
1 2 2 3 3 3 4 4 4 4 5 5 5 5 5 ...
(the number is repeated as many times, to what it equals to).
I've used two for loops, however, I can't get 1 to print once, 2 to print twice, instead, I get
1 2 3 4 5 6 1 2 3 4 5 6, etc.

You need two for loops for this.
for (int i = 0; i <= 5; i++) { // This will loop 5 times
for (int j = 0; j < i; j++) { //This will loop i times
System.out.print(i);
}
}

As I remember the goal is to print n numbers (for example 1 2 2 3 3 3 4 for n = 7), diveded by space. Sorry for my java)), I wrote it in Kotlin, tried to change for Java, but main idea is clear. BTW n – the number of the elements, you need to read with Scanner.
int count = 0 //Idea is to create a counter, and to increment it each time of printing
for (int i = 0; i <= n; i++) { //Loops n times
for (int j = 0; j < i; j++) { //Loops i times
if (int count < int n) {
System.out.print(" "+i+" ");
int count++ //Prints 1 one time, 2 two times, etc. stops if reached n number
}
}
}

How about this :
for(int i=1;i<=num;i++){
for(int j=1;j<=i;j++){
System.out.print(" "+i+" ");
}
}
where, num = 1,2,....n
(Also we wont be able to tell why you got that output unless you attach the code. Please attach the code snippets for such questions :) !

Nested for loop output printing and formatting incorrect table, it's all funky

So the goal was to use a nested for loop to output 6 rows and 10 columns. The thing was though that the inner for loop was supposed to check to see whether the number was even or odd as, if it was even, we would add 2 to it and then print out that number 10 times before moving onto the next output. So this is what were were supposed to get
1 1 1 1 1 1 1 1 1 1
4 4 4 4 4 4 4 4 4 4
3 3 3 3 3 3 3 3 3 3
6 6 6 6 6 6 6 6 6 6
5 5 5 5 5 5 5 5 5 5
8 8 8 8 8 8 8 8 8 8
I thought I was on the right track but my output is a complete mess, here's what I have. Thank you to anyone willing to help.
for (int numberE = 1; numberE <= 6; numberE++)
{
for (int nestedE = 1; nestedE < 10; nestedE++)
{
if (numberE%2 == 0)
{
numberE += 2;
System.out.printf("%2d", numberE);
} else {
System.out.printf("%2d", numberE);
}
}
System.out.printf("%2d\n", numberE);
}

well to start with your inner loop will only iterate nine times. second you don't need a nested loop, you need one loop and a guard determining when to print.

Don't modify numberE inside the loops. Instead just print numberE + 2.
Also, if your inner loop runs from 0 to <10 you will get 10 iterations and you don't need to print the number again - just a newline.
for (int numberE = 1; numberE <= 6; numberE++)
{
for (int nestedE = 0; nestedE < 10; nestedE++) // <-- start at 0 and end <10 for 10 iterations
{
if (numberE%2 == 0)
{
System.out.printf("%2d", numberE + 2); // <-- print the number + 2
} else {
System.out.printf("%2d", numberE);
}
}
System.out.println(); // <-- don't print the value again here
}

I would do it this way. Gives the required result.
public class NestedForLoop {
public static void main(String[] args) {
for (int i = 1; i <= 6; i++)
{
int temp = i;
if(temp%2 == 0) {
temp +=2;
}
for(int j=1;j<=10;j++) {
System.out.print(temp+" ");
}
System.out.println();
}
}
}
A brief description of what is happening here:
So, since we need 6 rows, we use the value of 6 as a row counter. The variable i takes care of keeping a count of the rows. Here since the target is 6, we start from row number 1 and go until row no 6. Inside each value of the loop, we save the value of i to temp because we don't want the value of i to change before incrementing in the main for loop. We then check if this temp value is even by doing a modulo division by 2. If it is even, we increment the temp value by 2.
Then, we run a loop from 1 to 10 since we need 10 columns to print the value temp(either the original i or incremented because it was even). After exiting the loop, finally to move to the next row, we do a System.out.println().

I would suggest using a temporary variable to store the current intended value.
The issue with your solution was that you were modifying the value of numberE by using numberE += 2; inside the second for loop, this changes the value globally.
Moving the final column in to the nested for loops also makes it easier as you wouldn't need to define the temporary variable outside of the loop. Using this also meant changing the <10 to <=10.
for (int numberE = 1; numberE <= 6; numberE++) {
for (int nestedE = 1; nestedE <= 10; nestedE++) {
int current = (numberE % 2 == 0) ? numberE + 2 : numberE;
System.out.printf("%2d", current);
}
System.out.printf("\n");
}
You were pretty close though, with practise you'll get better.

Replacing Multiples of numbers in Fibonacci series using Flag method

As the title suggests, I have code for a Fibonacci series and my goal is to replace multiples of numbers (3, 5, 7 and combinations of them) in the series with a word. I was suggested to use a flag in my if loop to check for the printed phrase, and if the phrase is printed, to skip that number. Essentially, what I want the output to look like is:
1 1 2 skip 8 13 skip 34 55
(this is replacing multiple of three only, for now).
Instead, what I am getting is:
1 1 2 3 skip5 8 13 21 skip34 55
Here is my code as of now:
int febCount = 50;
long[] feb = new long[febCount];
feb[0] = 1;
feb[1] = 1;
for (int i = 2; i < febCount; i++) {
feb[i] = feb[i - 1] + feb[i - 2];
}
for (int i = 0; i < febCount; i++) {
System.out.print(feb[i] + ((i % 10 == 9) ? "\n" : " "));
if (feb[i] % 3 == 0)
System.out.print("skip");
}
Any and all help is appreciated!

Let's walk through the code you have provided and attempt to understand why it's not working.
//The first thing we do is setup the loop to iterate through the fib numbers.
//This looks good.
for (int i = 0; i < febCount; i++) {
//Here we print out the fibonacci number we are on, unconditionally.
//This means that every fibonacci number will be printed no matter what number it is
//we don't want that.
System.out.print(feb[i] + ((i % 10 == 9) ? "\n" : " "));
//After we print the number, we check to see if it is a multiple of three.
//maybe we should be waiting to print until then?
if (feb[i] % 3 == 0)
System.out.print("skip");
}
Now that we have walked through the code, we can propose a new solution.
Let's try updating the loop so that it wait's to print the fibonacci number until AFTER we've checked to see if it meets our conditions.
for (int i = 0; i < febCount; i++) {
if (feb[i] % 3 == 0 || feb[i] % 5 == 0 || feb[i] % 7 == 0) { //check if multiple of 3 5 or 7
System.out.println(" Skip ");
} else { //if it's not a multiple, then print the number
System.out.println(" " + feb[i]);
}
}

For loop to print the number in sequence and reverse it

How to print the following output with only one for-loop in java?
1 2 3 4 5 6 7 8 9 1 0 9 8 7 6 5 4 3 2 1
Code snippet:
class Series{
public static void main(String args[]){
for(int i=1; i<=10; i++){
System.out.println(i);
}
System.out.println(i);
for(int j=9; j>=0; j--){
System.out.println(j);
}
}
My program's in the following manner. Can anyone correct it?

public static void main(String...strings ){
int dir = 1;
for(int i=1; i>0; i+=dir){
if(i == 10)
dir = -1;
System.out.print(i+" ");
}
}
Output:
1 2 3 4 5 6 7 8 9 10 9 8 7 6 5 4 3 2 1

The series in the question is wrong.
It should be: 1 2 3 4 5 6 7 8 9 10 9 8 7 6 5 4 3 2 1
The code, in one loop, is as follows:
int ctr = 1;
for(int i = 1; i > 0; i += ctr)
{
if(i == 10)
{
ctr = -1;
}
System.out.print(i + " ");
}

Every sequence follows a pattern, Let's try finding one in this.
To work with this code, analyze What loop would print with the variable that you increment and What you want in the output?
In your problem, assuming that the number you are entering is entered by user i.e. n, you want 2*n - 1 numbers in your sequence. Hence we now have the limits of our loop
For n=5, Under no Conditions the loop would simply print a sequence like this
1 2 3 4 5 6 7 8 9 provided you are starting your loop from 1.
The sequence you want is 1 2 3 4 5 4 3 2 1.
Now looking at both the sequences you can see that the sequence is same till the mid point that is till the value of n is reached. Now if you observe the pattern further if you subtract 2 from 6 you get 4 that is the number you want in your sequence. Similarly when you subtract 4 from 7 you get 3 which is the next number in the sequence you required.
Hence the pattern this sequence follows is that after the loop reaches the value provided by the user you need to subtract (2 * k) from the next number where k starts from 1 and increases with every iteration
Now you know how to achieve the pattern which would be easy to achieve using conditional statements.
PS: let's assume an added constraint of using no conditional statements then we have to write an arithmetic expression to solve our problem.
Following the pattern again the expression must display i where i is the variable incremented in the loop
so our code looks like
for (i = 1; i<=2*n - 1;i++)
{
System.out.print(i);
}
Now to get the pattern we need to subtract multiples of 2 after the user provided integer n is reached. But whatever we subtract should also not affect out first n integers.
Since we know we have to subtract multiples of 2 we know the expression we have to subtract would look like 2 * (____). As we want a sequence of multiples we can obtain that using %. As soon as the number goes over n the % operator on i would give us back sequence from 0 to n-1 hence generating multiples of 2.
Now our expression comes to 2 * (i % n). But the problem is that it would also subtract from the first 4 integers which we don't want so we have to make changes such that this expression will work only after loop reaches the value provided by the user.
As we know the division / operator provides us with the quotient. Hence it would yield us 0 till we reach the value of user defined number and 1 for the rest of the sequence as we run our loop till 2*n -1. Hence multiplying this expression to our previous expression yields 2*(i%n)*(i/n)
And there we have it our final code to generate the sequence would be
for (int i = 1;i<2*r;i++)
{
System.out.print(i - 2 * (i%r)*(i/r));
}
Observe the above code for the first n-1 integers i/r would make subtracted expression 0 and for i = n, i % r would make the expression 0. For the rest of the sequence i / r would generate value 1 and hence we will get multiples of 2 from 2 *( i % r) to provide us with the sequence

try this
int j = 10;
for (int i = 1; i <= 10; i++) {
if(i<10)
System.out.print(" " +i);
if(i==10){
i--;
System.out.print(" " +j);
if(j==1){
i++;
}
j--;
}
}
OutPut
1 2 3 4 5 6 7 8 9 10 9 8 7 6 5 4 3 2 1

Something like this?
for(int i=0;i<20;i++) {
if((i/10)%2 == 0)
System.out.print(i%10 + " ");
else
System.out.print((10-(i%10)) + " ");
}

Try this code, You just need a if condition in for loop.
int i = 1;
for(int j=1; j<=20; j++)
{
if(j<11)
System.out.print(j+" ");
else
{
System.out.print((j - i == 10 ?" ": (j-i + " ")));
i = i+2;
}
}

public class forLoopTest {
public static void main(String[] args) {
for (int i = 1; i < 10; i++) {
System.out.print(i + " ");
}
for (int j = 10; j >= 1; j--) {
System.out.print(j + " ");
}
}
}