Power of Two Triangle

MultiplicativeTriangle.java

/**
 * To run this:
 *
 * 1. Compile it.
 *
 * javac MultiplicativeTriangle.java
 *
 * 2. Run it.
 *
 * java MultiplicativeTriangle
 */

public class MultiplicativeTriangle {

    // Calculate the number of columns for a given row
    public static int columns(int row) {
        return 2 * row - 1;
    }

    // Generate spaces as a string
    public static String space(int n) {
        return n > 0 ? " ".repeat(n) : "";
    }

    public static void main(String[] args) {
        int rows = 7;

        // Precompute powers of 2 up to the maximum value required
        int[] powers = new int[rows + 1];
        for (int power = 0; power <= rows; power++) {
            powers[power] = (int) Math.pow(2, power);
        }

        // Compute the maximum row width (for centering)
        int maxRowWidth = 0;
        for (int power = 0; power < rows; power++) {
            maxRowWidth += String.valueOf(powers[power]).length() * 2;
        }
        maxRowWidth += String.valueOf(powers[rows - 1]).length() + (columns(rows) - 1);

        // Generate and print each row
        for (int row = 1; row <= rows; row++) {
            int columns = columns(row);

            // Compute the current row's width
            int currentRowWidth = 0;
            for (int i = 0; i < row - 1; i++) {
                currentRowWidth += String.valueOf(powers[i]).length() * 2;
            }
            currentRowWidth += String.valueOf(powers[row - 1]).length() + (columns - 1);

            // Center the row
            int middle = (maxRowWidth - currentRowWidth) / 2;
            int before = (int) Math.ceil(middle);
            int after = (int) Math.floor(middle);

            // Print leading spaces
            System.out.print(space(before));

            // Print the values for the row
            for (int column = 1; column <= columns; column++) {
                int power = column < row ? column - 1 : columns - column;
                System.out.print(powers[power]);
                if (column < columns) {
                    System.out.print(" ");
                }
            }

            // Print trailing spaces and row terminator
            System.out.print(space(after) + " @\n");
        }
    }
}

triangle.php

<?php
function columns(int $row): int {
    return 2 * $row - 1;
}
function space(int $n): string {
    return $n > 0 ? str_repeat(' ', $n) : '';
}
$rows = 7;
$powers = array_map(fn(int $power) => 2**$power, range(0, $rows));
$width = fn(int $row): int => array_sum(array_map('strlen', array_slice($powers, 0, $row - 1))) * 2 + strlen($powers[$row - 1]) + (columns($row) - 1);
for ($row = 1; $row <= $rows; $row++) {
    $columns = columns($row);
    $length = $width($row);
    $middle = ($width($rows) - $length) / 2;
    $before = ceil($middle);
    $after = floor($middle);
    echo space($before);
    for ($column = 1; $column <= $columns; $column++) {
        $power = $column < $row ? $column - 1: $columns - $column;
        echo $powers[$power], ' ';
    }
    echo space($after) . " @\n";
}