Question

A php solution to a question "find the first pair that adds up to 10". Refresh for another random array.

Answer by Rachel C

[2, 2, 10, 8, 10, 5]

First pair = 0, 3.

Other pair --
First pair = 0, 3.


<?php

# randomly generate an array

$arrayLength = rand(3, 20);
$arr = array();

for ($i = 0; $i < $arrayLength; $i++) {
	array_push($arr, rand(0, 10));
}

print "[";
for ($i = 0; $i < $arrayLength; $i++) {
	if ($i > 0) print ", ";
	print $arr[$i];
}
print "]";
print "

";


$match = getFirstPair($arr);
printMatch($match);
print "

Other pair -- 
";
$match = getFirstPairDouble($arr);
printMatch($match);

function printMatch($match) {
	if (count($match) == 2) {
		print "First pair = " . $match[0] . ", " . $match[1] . ".";
	} else {
		print "No pair that adds to 10.";
	}
}



function getFirstPair($arr)  {
	$hashMap = array();
	for ($i = 0; $i < 11; $i++) {
		$hashMap[$i] = -1;
	}

	for ($i = 0; $i < count($arr); $i++) {
		$value = $arr[$i];
		$match = 10 - $value;
		if ($hashMap[$match] >= 0) {
			return array($hashMap[$match], $i);
		}
		if ($hashMap[$value] == -1) $hashMap[$value] = $i;
	}
}


function getFirstPairDouble($arr)  {
	for ($i = 1; $i < count($arr); $i++) {
		for ($j = 0; $j < $i; $j++) {
			if ($arr[$i] + $arr[$j] == 10) {
				return array($j, $i);
			}
		}
	}

}
?>