Untitled

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    <title>Document</title>
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<body>
    <script>
        let numbers = [0, 1, 2, 3, 4, 5, 6, 7];
        let k = 4;

        let random_numbers = get_random_numbers(numbers, k);

        console.log(random_numbers);

        function get_random_numbers(numbers, k) {
            let result = new Array();
            get_random_numbers_helper(numbers, k, 0, numbers.length - 1, result);

            return result;
        }

        function get_random_numbers_helper(numbers, k, start, end, result) {
            if (result.length == k || end == -1 || start > end) {
                return result;
            }

            let random_index = Math.floor(Math.random() * (end - start + 1)) + start;
            let new_number = numbers[random_index];

            result.push(numbers[random_index]);

            get_random_numbers_helper(numbers, k, start, random_index-1, result);
            get_random_numbers_helper(numbers, k, random_index+1, end, result);
        }
    </script>
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