public void Test1()
        {
            int[]    nums     = new int[] { 1, 2, 3, 3, 3 };
            Solution solution = new Solution(nums);

            // pick(3) should return either index 2, 3, or 4 randomly. Each index should have equal probability of returning.
            var four = solution.Pick(3);

            // pick(1) should return 0. Since in the array only nums[0] is equal to 1.
            var one = solution.Pick(1);

            Assert.AreEqual(one, 0);
        }