Calculate at least 3 minimum and maximum numbers from array - php

Question

Code
<?php
$array = array("1", "2", "3", "4", "5", "6", "7", "8", "100");
$max = $temp = 0;
$min = $temp = 0;
//This loop is to get max and min value from array
for ($i = 0 ; $i < count($array); $i++) {
if ($i == 0) {
$max = $temp = $array[$i];
}
if ($i > 0) {
if ($array[$i] > $temp) {
$max = $array[$i];
}
}
if ($i == 0) {
$min = $temp = $array[$i];
}
if ($i < 0) {
if ($array[$i] < $temp) {
$min = $array[$i];
}
}
}
echo "Max Number = $max <br>";
echo "Min Number = $min";
?>
The above code only calculates one minimum and one maximum number from the array. I need it to calculate 3 maximum and 3 minimum numbers.
I can't use pre-made functions and can't use more than one for loop so kindly suggest me customization within the above code.

Answer 1

This looks neat to me.
<?php
$array = array("1", "2", "3", "4", "5", "6", "7", "8", "100");
$n1 = $n2 = $n3 = 1000 ; // some high number
$m1 = $m2 = $m3 = 0 ;
//This loop is to get max and min value from array
for ($i = 0 ; $i < count($array); $i++) {
$x = $array[$i] ;
//min
if ($x <= $n1){
$n3 = $n2 ;
$n2 = $n1 ;
$n1 = $x ;
} elseif ($x < $n2){
$n3 = $n2;
$n2 = $x;
} elseif ($x < $n3){
$n3 = $x;
}
//max
if ($x >= $m1){
$m3 = $m2 ;
$m2 = $m1 ;
$m1 = $x ;
} elseif ($x > $m2){
$m3 = $m2;
$m2 = $x;
} elseif ($x > $m3){
$m3 = $x;
}
}
echo "Min Number = $n1 $n2 $n3<br>";
echo "Max Number = $m1 $m2 $m3";
?>
Output:
Min Number = 1 2 3
Max Number = 100 8 7

Answer 2

This code is working properly
<?php
$array = array("1", "2", "3", "4", "5", "6", "7", "8", "100");
$max1 =$max2 =$max3= -999999999999999; // highest possible number
$min3 = $min2= $min1 = 9999999999999999; // lowest possible number
for ($i = 0 ; $i < count($array); $i++) {
$x = $array[$i] ;
//to get the max 3 numbers
if($x>= $max1)
{
$max3 = $max2;
$max2 = $max1;
$max1 = $x;
}
else if ($x> $max2)
{
$max3 = $max2;
$max2 = $x;
}
else if ($x> $max3)
{
$max3 = $x;
}
// to get the min 3 numbers
if($x<=$min3 && $x>$min2 )
{
$min3 = $x;
}
else if ($x<$min2 && $x>$min1)
{
$min3 = $min2;
$min2 = $x;
}
else if ( $x<$min1)
{
$min3 = $min2;
$min2 = $min1;
$min1 = $x;
}
}
echo "Max Number = $max1 , $max2 , $max3 <br>";
echo "Min Number = $min1 , $min2 , $min3";
?>
The output is
Max Number = 100 , 8 , 7
Min Number = 1 , 2 , 3
There are better ways and more efficient than that but which requires 2 loops and u don't want that !

Answer 3

You can handle this using if statements
Checking for the max/min number works when you find another min/max value other than the previous one while looping. This is the algorithm that you use
Lets assume that your min=5
and after looping the current index value is 3, so you will have to make min=3
What about assigning 5 to min2 for example?
Three variables min1, min2, min3, and nested if statements
I know it's not the best way. But have you tried this?

Answer 4

You just need to reverse sort the array and then slice the first three indexes. You could express it as a function:
function topThree(Array $arr) {
// Sort the array in reverse
rsort($arr);
// Return the first three indexes (top three)
return array_slice($arr, 2);
}
See rsort and array_slice
Edit: Okay this works
/**
* Sorts an array of numeric values from largest to
* smallest and returns the three highest values.
*
* #param Array $arr An array of numeric values.
* #return Array $srt The three highest values in $arr.
*/
function topThree(Array $arr) {
$srt = [];
foreach($arr as $key => $val) {
if(!$key) {
$srt[] = $val;
} else if ($val < $srt[0]) {
array_unshift($srt, $val);
} else if ($val > $srt[count($srt)-1]) {
array_push($srt, $val);
} else {
for( $i=1; $i<count($srt); $i++) {
if($val < $srt[$i]) {
array_splice( $srt, $i, 0, $val );
break;
}
}
}
}
$max = array_slice($srt, -3, 3);
$min = array_slice($srt, 0, 3);
return ["min" => $min, "max" => $max];
}
// "Test"
for($i=0; $i<20;$i++){
$arr[]=rand(-100,100);
}
print_r($arr);
print_r(topThree($arr));
If $val's the first $key $val's added to $sort.
If $val's less than $sort[0] $val's added to the start of $sort.
If $val's greater than $sort[length], then $val's added to the end of $sort.
Otherwise, we check every $val against every other $sort value. When we find a $sort[$i] value greater than $val, we splice the array with $val at $i.
Make sense?