Can this code be further reduce , maybe without variable "k" (in this example)

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JAVA

In this code, I have to use 7 for loops and assign the variable k. Is there any way to reduce the time complexity of this code, maybe without variable "k"

Here is my code:

import java.util.Scanner;
public class PracticePattern6 {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
int k=1;
for(int i=0;i<2*n+1;i++)
{
if(i<n+1)
{
for(int j = i ;j<n;j++)
{ 
System.out.print("* ");
}
for(int j =0;j<2*i+1;j++)
{
System.out.print("  ");
}
for(int j = i ;j<n;j++)
{
System.out.print("* ");
}
}
else
{
for(int j=0;j<i-n;j++)
{
System.out.print("* ");
}
for(int j=0;j<2*n-k;j++)
{
System.out.print("  ");
}
for(int j=0;j<i-n;j++)
{
System.out.print("* ");
}
k+=2;
}
System.out.println();
}
sc.close();
}
}

I believe this is a little simpler, however I did not do a side by side check to make sure they have the exact same output, if they do not the outputs are very similar and with a little tweaking you could make this code work for the exact correct output I believe.

public static void main(String[] args) throws InterruptedException {
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
for(int i = 0;i<n;i++) {
for(int j = 0;j<n-i;j++) {
System.out.print("* ");
}
for(int j = 0;j<i*2;j++) {
System.out.print("  ");
}
for(int j = 0;j<n-i;j++) {
System.out.print(" *");
}
System.out.println();
}
for(int i = n;i>=0;i--) {
for(int j = n;j>i;j--) {
System.out.print("* ");
}
for(int j = n;j>n-i*2;j--) {
System.out.print("  ");
}
for(int j = n;j>i;j--) {
System.out.print(" *");
}
System.out.println();
}

If it is allowed to use an intermediate array of Strings/chars to build the entire picture before printing it, it can be done in the following way:

1. Create entire field and populate it with required patterns for the left and right halves (using standard Arrays.fill method).
2. Set "empty" cells for top and bottom halves of the field, calculating the left and right position of the empty space.
3. Print the field.

Example:

public static void printRhombPattern(int size, String leftPattern, String rightPattern, String empty) {
    int cols = 2 * size;
    int rows = cols + 1;

    String[][] field = new String[rows][cols];
    for (int i = 0; i < rows; i++) {
        field[i] = new String[cols];
        Arrays.fill(field[i], 0, size, leftPattern);
        Arrays.fill(field[i], size, cols, rightPattern);
    }
        
    int left = cols / 2 - 1;
    // starting from i == 1 to skip the first and the last rows
    for (int i = 1, right = left + 1; i <= size; i++, left--, right++) {
            
        for (int j = left; j <= right; j++) {
            field[i][j] = empty;             // clean cells in the top half
            field[rows - 1 - i][j] = empty;  // clean cells in the bottom half
        }
    }

    // main printing
    for (int i = 0; i < rows; i++) {
        for (int j = 0; j < cols; j++) {
            System.out.print(field[i][j]);
        }
        System.out.println();
    }
}

// test
public static void main(String[] args) {
    printRhombPattern(5, "* ", " *", "  ");
}

Output:

* * * * *  * * * * *
* * * *      * * * *
* * *          * * *
* *              * *
*                  *
*                  *
* *              * *
* * *          * * *
* * * *      * * * *
* * * * *  * * * * *

Short Answer: No.

If you talk about the time complexity, the big-O of the specified code for printing the diamond whitespace.

 https://ideone.com/foelhX

The current solution is O(N^2) which is minimal to print 2-D shape.
moreover, you can reduce some constants, that would not impact your time complexity.
<br>
In case you are starting programming, this would be a helpful resource:

https://github.com/joney000/Java-Competitive-Programming