var sol = new Solution();

var cases = new (int[] input, int[] expected)[]
{
	(new[] { 1, 2, 3 }, new[] { 1, 3, 2 }),
	(new[] { 3, 2, 1 }, new[] { 1, 2, 3 }),
	(new[] { 1, 1, 5 }, new[] { 1, 5, 1 })
};

foreach (var (input, expected) in cases)
{
	var nums = (int[])input.Clone();
	sol.NextPermutation(nums);
	var status = AreEqual(nums, expected) ? "ok" : "fail";
	Console.WriteLine($"{Format(input)} -> {Format(nums)} (expected: {Format(expected)}) {status}");
}

static string Format(int[] nums) => $"[{string.Join(",", nums)}]";

static bool AreEqual(int[] left, int[] right)
{
	if (left.Length != right.Length)
		return false;
	for (var i = 0; i < left.Length; i++)
	{
		if (left[i] != right[i])
			return false;
	}
	return true;
}