Arrays and Iteration

Find Maximum

Scan the array once, keeping the largest value seen so far. The replay highlights when a candidate replaces the running maximum.

Algorithm

Basic Implementation

basic.php 
<?php
$arr = [3, 1, 4, 1, 5, 9, 2, 6];
$best = $arr[0];
for ($i = 1; $i < count($arr); $i++) {
	if ($arr[$i] > $best) {
		$best = $arr[$i];
	}
}
echo $best . "\n";

Complexity

  • Time: O(n)
  • Space: O(1)

Implementation notes

  • $arr is a PHP array literal with the pinned values [3, 1, 4, 1, 5, 9, 2, 6].
  • $best = $arr[0] seeds the running maximum with 3 before the loop starts.
  • The scan uses an indexed for loop: $i = 1; $i < count($arr); $i++, so each later element is read as $arr[$i].
  • The array is never mutated; only $best and $i change during the scan.
  • The update condition is strict greater-than: if ($arr[$i] > $best) { $best = $arr[$i]; }.
  • The trace shows replacements at i = 2 (4), i = 4 (5), and i = 5 (9); later values 2 and 6 do not replace it.
  • echo $best . "\n"; prints the final scalar value 9 with a newline.
execution replay The checked-in replay follows the language-neutral state table for `array-find-max`.
cross-language comparison This PHP DSA version keeps the same data and final output as every other DSA book in this wave.