PHP Exercises: Find the maximum sum of a contiguous subsequence from a given sequence of numbers a1, a2, a3, ... an

Last update on May 30 2022 11:48:30 (UTC/GMT +8 hours)

PHP: Exercise-57 with Solution

Write a PHP program to find the maximum sum of a contiguous subsequence from a given sequence of numbers a1, a2, a3, ... an. A subsequence of one element is also a continuous subsequence.

Input:You can assume that 1 ≤ n ≤ 5000 and -100000 ≤ ai ≤ 100000.
Input numbers are separated by a space.
Input 0 to exit.

Pictorial Presentation:

PHP: Find the maximum sum of a contiguous subsequence from a given sequence of numbers a1, a2, a3, ... an.

Sample Solution: -

PHP Code:

<?php
while($line = fgets(STDIN)){
	$n = intval($line);
	if($n == 0){
		break;
	}	
	$arr = array();
	$max_val = array();
	for($i = 0; $i < $n; $i++){
		$x = intval(fgets(STDIN));
		$arr[$i] = 0;
		$max_val[$i] = -1000000;
		for($j = 0; $j <= $i; $j++){
			$arr[$j] += $x;
			if($max_val[$j] < $arr[$j]){
				$max_val[$j] = $arr[$j];
			}
		}
	}
	
	echo max($max_val)."\n";
}
?>

Sample Input:
6
-4
-2
5
3
8

Sample Output:

Flowchart:

PHP Code Editor:

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Previous: Write a PHP program to test whether two lines PQ and RS are parallel.
The four points are P(x1, y1), Q(x2, y2), R(x3, y3), S(x4, y4).
Next: Write a PHP program to test the specified Circumference of C1 and C2 intersect.

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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