Algorithms: Range Queries

int fenwick_sum(const std::vector<int>& tree, int end) {
    alg_require(tree.size() <= 1000000);
    int n = alg_sub((int)tree.size(), 1);
    alg_require(((n >= 0) && (n <= 1000000)));
    alg_require(((int)tree.size() == alg_add(n, 1)));
    alg_require(((end >= 0) && (end <= n)));
    int total = 0;
    while ((end > 0)) {
        total = alg_add(total, tree[end]);
        end = alg_sub(end, (end & alg_sub(0, end)));
    }
    return total;

    static int fenwick_sum(ReadOnlySpan<int> tree, int end) {
        checked {
            int n = (tree.Length - 1);
            alg_require(((n >= 0) && (n <= 1000000)));
            alg_require((tree.Length == (n + 1)));
            alg_require(((end >= 0) && (end <= n)));
            int total = 0;
            while ((end > 0)) {
                total = (total + tree[end]);
                end = (end - (end & (-end)));
            }
            return total;

function fenwick_sum(array $tree, int $end): int {
    alg_require(array_is_list($tree));
    $n = alg_sub(count($tree), 1);
    alg_require((($n >= 0) && ($n <= 1000000)));
    alg_require((count($tree) == alg_add($n, 1)));
    alg_require((($end >= 0) && ($end <= $n)));
    $total = 0;
    while (($end > 0)) {
        $total = alg_add($total, $tree[$end]);
        $end = alg_sub($end, ($end & alg_sub(0, $end)));
    }
    return $total;

    static int fenwick_add(int[] tree, int index, int delta) {
        java.util.Objects.requireNonNull(tree, "tree");
        int n = Math.subtractExact(tree.length, 1);
        alg_require(((n >= 0) && (n <= 1000000)));
        alg_require((tree.length == Math.addExact(n, 1)));
        alg_require(((index >= 0) && (index < n)));
        index = Math.addExact(index, 1);
        while ((index <= n)) {
            tree[index] = Math.addExact(tree[index], delta);
            index = Math.addExact(index, (index & Math.negateExact(index)));
        }
        return 0;

function fenwick_add(tree, index, delta) {
    alg_require(tree instanceof Int32Array);
    alg_require(Number.isInteger(index) && index >= -2147483648 && index <= 2147483647);
    alg_require(Number.isInteger(delta) && delta >= -2147483648 && delta <= 2147483647);
    let n = alg_sub(tree.length, 1);
    alg_require(((n >= 0) && (n <= 1000000)));
    alg_require((tree.length == alg_add(n, 1)));
    alg_require(((index >= 0) && (index < n)));
    index = alg_add(index, 1);
    while ((index <= n)) {
        tree[index] = alg_add(tree[index], delta);
        index = alg_add(index, (index & alg_sub(0, index)));