Method select

java/0347-top-k-frequent-elements.java:51–65

(
        int[] keys,
        Map<Integer, Integer> map,
        int left,
        int right,
        int kSmallest
    )

    // Modified implementation of Hoare's selection algorithm:

    private void select(
        int[] keys,
        Map<Integer, Integer> map,
        int left,
        int right,
        int kSmallest
    ) {
        while (left != right) {
            int pivot = partition(keys, map, left, right, (left + right) / 2);

            if (kSmallest == pivot) return;

            if (kSmallest < pivot) right = pivot - 1; else left = pivot + 1;
        }
    }

    private int partition(
        int[] keys,