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

Last update on May 26 2025 13:17:18 (UTC/GMT +8 hours)

46. Top Three Building Heights

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
// Create an empty array to store building heights
$heights = array();

// Read input from STDIN until end-of-file
while ($line = fgets(STDIN)) {
    // Remove newline characters and convert to integer, then push to the heights array
    rtrim($line, "\n");
    array_push($heights, (int)$line);
}

// Sort the heights array in descending order
rsort($heights);

// Print the top three building heights
print("Heights of the top three buildings:\n");
echo $heights[0]."\n"; // Print the height of the tallest building
echo $heights[1]."\n"; // Print the height of the second tallest building
echo $heights[2]."\n"; // Print the height of the third tallest building

?>

Explanation:

Array Initialization:

An empty array called $heights is created to store the heights of buildings.

Reading Input:

A while loop is used to read input from the standard input (STDIN) line by line until the end-of-file (EOF) is reached.
fgets(STDIN) reads a line of input.

Processing Input:

Each line is processed to remove any trailing newline characters using rtrim($line, "\n").
The line is then converted to an integer using (int)$line and pushed into the $heights array using array_push().

Sorting Heights:

The rsort($heights) function sorts the $heights array in descending order, meaning the tallest buildings will appear first.

Output Top Three Heights:

A message is printed to indicate that the top three building heights will be displayed.
The first three elements of the sorted $heights array (i.e., the tallest, second tallest, and third tallest buildings) are printed using echo.

Prints:

echo $heights[0]."\n" prints the height of the tallest building.
echo $heights[1]."\n" prints the height of the second tallest building.
echo $heights[2]."\n" prints the height of the third tallest building.

Output:

Heights of the top three buildings:
45
25
24

Flowchart:

For more Practice: Solve these Related Problems:

Write a PHP script to extract the top three maximum values from an array of building heights.
Write a PHP script to sort an array of building heights and output the three tallest values.
Write a PHP function to retrieve three unique maximum heights from a list using custom sorting.
Write a PHP script to filter building heights and display the top three using an optimized algorithm.

Go to:

PREV : Sum of Digits.
NEXT : Digit Count of Sum.

PHP Code Editor:

Have another way to solve this solution? Contribute your code (and comments) through Disqus.