three_ascending.php

<?php
function three_asc(array $a) {
    if (count($a) < 3) {
        return false;
    }
    $min = $max = $new_min = 0;
    for ($i = 1; $i < count($a); $i++) {
        if ($min < $max) {
            if ($a[$max] < $a[$i]) {
                return [$min, $max, $i];
            } elseif ($a[$min] < $a[$i]) {
                $max = $i;
            } elseif ($a[$new_min] < $a[$i]) {
                $min = $new_min;
                $max = $i;
            } else {
                $new_min = $i;
            }
        } else {
            if ($a[$max] < $a[$i]) {
                $max = $i;
            } elseif ($a[$i] < $a[$min]) {
                $min = $max = $i;
            }
        }
    }
    return false;
}

$test = [
    [
        [1, 2, 3],
        [0, 1, 2],
    ],
    [
        [4, 5, 3, 6, 4, 8, 10, 1],
        [0, 1, 3],
    ],
    [
        [9, 5, 3, 6, 4, 8, 10, 1],
        [2, 4, 5],
    ],
    [
        [1, 1, 2, 1, 3],
        [0, 2, 4],
    ],
    [
        [1, 2, 1, 2, 3],
        [0, 3, 4],
    ],
    [
        [],
        false,
    ],
    [
        [2, 3, 2, 2, 3, 2, 3, 2, 3, 3, 2, 1],
        false,
    ],
    [
        [6, 5, 4, 3, 2],
        false,
    ],
    [
        [1, 2, 1, 2, 1, 0, 1],
        false,
    ],
];

foreach ($test as $a) {
    echo '[' . implode(', ', $a[0]) . '] => ';
    $res = three_asc($a[0]);
    if ($a[1] == $res) {
        echo 'OK';
    } else {
        echo ' FAIL [' . implode(', ', $res) . ']';
    };
    echo "\n";
}