随机平铺中的滑动谜题帮助

我在创建滑动谜题时遇到问题。我正在尝试制作一种重置&打乱所有15个按钮，但问题是随机数字重复出现。

当我写bool[] usednum = new bool[array.length];时，我得到一个错误，所以我增加了usednum数组的长度。。。。。

private void reset()
{
    int[] array = { 1, 2, 3, 4, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 };
    int count = 0;
    Random r = new Random();
    bool[] usednum = new bool[50];
    for (int i = 0; i < usednum.Length; i++)
        usednum[i] = false;
    while (count < array.Length)
    {
        int temp = array[r.Next(array.Length)];
        if (usednum[temp] == false)
        {
            button1.Text = temp.ToString();
            usednum[temp] = true;
            count++;
        }
        temp = array[r.Next(array.Length)];
        if (usednum[temp] == false)
        {
            button2.Text = temp.ToString();
            usednum[temp] = true;
            count++;
        }
        temp = array[r.Next(array.Length)];
        if (usednum[temp] == false)
        {
            button3.Text = temp.ToString();
            usednum[temp] = true;
            count++;
        }
        temp = array[r.Next(array.Length)];
        if (usednum[temp] == false)
        {
            button4.Text = temp.ToString();
            usednum[temp] = true;
            count++;
        }
        temp = array[r.Next(array.Length)];
        if(usednum[temp] == false)
        {
            button5.Text = temp.ToString();
            usednum[temp] = true;
            count++;
        }
        temp = array[r.Next(array.Length)];
        if (usednum[temp] == false)
        {
            button6.Text = temp.ToString();
            usednum[temp] = true;
            count++;
        }
        /*.
        . 
        . 
        . to button 15*/

maxIndex = array.Length - 1
for index in 0 to maxIndex - 1
    swapIndex = random number between index and maxIndex
    swap (array, index, swapIndex)

var array = new int[] { 1, 2, 3, 4, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 };
var unused = array.ToList();
var r = new Random();
while (unused.Count > 0)
{
       int c = r.Next(unused.Count - 1);
       int current = unused[c];
       unused.RemoveAt(c);
       //...
}