Algorithms: Array Techniques

    static int is_palindrome(int[] a) {
        java.util.Objects.requireNonNull(a, "a");
        int n = a.length;
        alg_require(((n >= 0) && (n <= 1000000)));
        alg_require((a.length == n));
        int left = 0;
        int right = Math.subtractExact(n, 1);
        while ((left < right)) {
            if ((a[left] != a[right])) {
                return 0;
            }
            left = Math.addExact(left, 1);

function is_palindrome(array $a): int {
    alg_require(array_is_list($a));
    $n = count($a);
    alg_require((($n >= 0) && ($n <= 1000000)));
    alg_require((count($a) == $n));
    $left = 0;
    $right = alg_sub($n, 1);
    while (($left < $right)) {
        if (($a[$left] != $a[$right])) {
            return 0;
        }
        $left = alg_add($left, 1);

function maximum_subarray(array $a): int {
    alg_require(array_is_list($a));
    $n = count($a);
    alg_require((($n >= 0) && ($n <= 1000000)));
    alg_require((count($a) == $n));
    alg_require(($n >= 1));
    $ending = $a[0];
    $best = $a[0];
    $i = 1;
    while (($i < $n)) {
        $ending = max($a[$i], alg_add($ending, $a[$i]));
        $best = max($best, $ending);

    static int maximum_subarray(ReadOnlySpan<int> a) {
        checked {
            int n = a.Length;
            alg_require(((n >= 0) && (n <= 1000000)));
            alg_require((a.Length == n));
            alg_require((n >= 1));
            int ending = a[0];
            int best = a[0];
            int i = 1;
            while ((i < n)) {
                ending = Math.Max(a[i], (ending + a[i]));
                best = Math.Max(best, ending);

int maximum_subarray(const std::vector<int>& a) {
    alg_require(a.size() <= 1000000);
    int n = (int)a.size();
    alg_require(((n >= 0) && (n <= 1000000)));
    alg_require(((int)a.size() == n));
    alg_require((n >= 1));
    int ending = a[0];
    int best = a[0];
    int i = 1;
    while ((i < n)) {
        ending = alg_max(a[i], alg_add(ending, a[i]));
        best = alg_max(best, ending);