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PHP Exercises: Find heights of the top three building in descending order from eight given buildings

PHP: Exercise-46 with Solution

Write a PHP program to find heights of the top three building in descending order from eight given buildings.

Input:
0 ≤ height of building (integer) ≤ 10,000

Pictorial Presentation:

PHP: Find heights of the top three building in descending order from eight given buildings

Sample Solution: -

PHP Code:

<?php
  $heights = array();
  while($line = fgets(STDIN)) {
    rtrim($line, "\n");
    array_push($heights, (int)$line);
  }
  rsort($heights);
  print("Heights of the top three buildings:\n");
  echo $heights[0]."\n";
  echo $heights[1]."\n";
  echo $heights[2]."\n";
?>

Sample Output: 

Heights of the top three buildings:
45
25
24

Flowchart:

Flowchart: Find heights of the top three building in descending order from eight given buildings

PHP Code Editor:

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Previous: Write a PHP program to compute the sum of the digits of a number.
Next: Write a PHP program to compute the digit number of sum of two given integers.

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PHP: Tips of the Day

How to Sort Multi-dimensional Array by Value?

Try a usort, If you are still on PHP 5.2 or earlier, you'll have to define a sorting function first:

Example:

function sortByOrder($a, $b) {
    return $a['order'] - $b['order'];
}

usort($myArray, 'sortByOrder');

Starting in PHP 5.3, you can use an anonymous function:

usort($myArray, function($a, $b) {
    return $a['order'] - $b['order'];
});

And finally with PHP 7 you can use the spaceship operator:

usort($myArray, function($a, $b) {
    return $a['order'] <=> $b['order'];
});

To extend this to multi-dimensional sorting, reference the second/third sorting elements if the first is zero - best explained below. You can also use this for sorting on sub-elements.

usort($myArray, function($a, $b) {
    $retval = $a['order'] <=> $b['order'];
    if ($retval == 0) {
        $retval = $a['suborder'] <=> $b['suborder'];
        if ($retval == 0) {
            $retval = $a['details']['subsuborder'] <=> $b['details']['subsuborder'];
        }
    }
    return $retval;
});

If you need to retain key associations, use uasort() - see comparison of array sorting functions in the manual

Ref : https://bit.ly/3i77vCC