Find Closest Pair from Two Sorted Arrays in PHP

What is PHP?

PHP (Hypertext Preprocessor) is a popular scripting language designed for web development. It is widely used for creating dynamic and interactive web pages. PHP code can be embedded directly into HTML, allowing developers to mix PHP and HTML seamlessly. PHP can connect to databases, process form data, generate dynamic content, handle file uploads, interact with servers, and perform various server-side tasks. It supports a wide range of web development frameworks, such as Laravel, Symfony, and CodeIgniter, which provide additional tools and features for building web applications. PHP is an open-source language with a large community, extensive documentation, and a rich ecosystem of libraries and extensions.

PHP Program to find the Closest Pair from Two Sorted Arrays

Given two sorted arrays and a number x, find the pair whose sum is closest to x and the pair has an element from each array.

Input

ar1 = [1, 3, 5, 7, 9];
ar2 = [2, 4, 6, 8, 10];
x = 12;

Output

Output is 1 and 10 because 1+10=11 which is closer to 12.

Example

<?php

function printClosest($ar1, $ar2,
					$m, $n, $x)
{

	$diff = PHP_INT_MAX;
	$res_l;
	$res_r;
	$l = 0;
	$r = $n - 1;
	while ($l < $m and $r >= 0) {
	   if (abs($ar1[$l] + $ar2[$r] - $x) < $diff){
	      $res_l = $l;
		  $res_r = $r;
		  $diff = abs($ar1[$l] + $ar2[$r] - $x);
		}

		if ($ar1[$l] + $ar2[$r] > $x)
		   $r--;
		else
		   $l++;
   }
   echo "The closest pair is [", $ar1[$res_l], ", ", $ar2[$res_r], "] 
";
}
	$ar1 = array(1, 4, 8, 10);
	$ar2 = array(2, 6, 9);
	$m = count($ar1);
	$n = count($ar2);
	$x = 20;
	printClosest($ar1, $ar2, $m, $n, $x);
?>

Output

The closest pair is [10, 9]

Conclusion

In Summary, The provided PHP program employs a two-pointer technique to efficiently find the closest pair from two sorted arrays. It begins by initializing the difference between the pair sum and the given number, "x," as a maximum value. The program maintains two result indexes, res_l and res_r, to store the indices of the closest pair. By comparing the absolute difference of the current pair's sum with x, the program continuously updates the closest pair whenever a closer pair is encountered. It adjusts the pointers based on whether the current sum is greater or smaller than x, effectively narrowing down the search space.

The program's time complexity is dependent on the sizes of the input arrays, m and n, as it performs a linear scan while traversing both arrays once. Therefore, it has a complexity of O(m + n). The PHP program offers an efficient solution to finding the closest pair from two sorted arrays with a sum closest to the given number x. By utilizing a two-pointer approach, it provides a streamlined method for identifying the pair with the minimum absolute difference, providing flexibility and accuracy in various scenarios.