Random random = new Random();
int[] dice = new int[5];
bool[] reroll_toggle = new bool[5];
int max_rerolls = 2;
int rerolls_left = max_rerolls;
// dice[] store 1..6 and k input will be '1'..'6'
// so to make it easier on my brain, i'll
// index singles[] with 1..6 and ignore singles[0]
int[] singles = new int[] { 0, -1, -1, -1, -1, -1, -1 };
int kind3 = -1;
int kind4 = -1;
int full = -1;
int small = -1;
int large = -1;
int kind5 = -1;
int chance = -1;
int extra_yahtzees = 0;
while (true)
{
    Console.Clear();
    score_card();
    Console.Write("\npress a key to roll dice...");
    if (!reroll_toggle.Contains(true))
        Console.ReadKey(true);
    Console.Write("\n\n");
    roll_dice();
    reroll_toggle = new bool[5];
    for (int i = 0; i < 5; i++)
        Console.Write("[" + dice[i] + "] ");
    Console.Write("\n\n(" + rerolls_left + " rerolls left)");
    Console.Write("\nchoose scoring");
    if (rerolls_left > 0) Console.Write(" or press r to reroll");
    Console.Write("...");
    bool got_input = false;
    bool scored = false;
    while (!got_input)
    {
        char k = Console.ReadKey(true).KeyChar;
        if ("12345678fsl90r".Contains(k))
        {
            if (k >= '1' && k <= '6')
            {
                int digit = k - '0';
                if (singles[digit] == -1)
                {
                    singles[digit] = count_singles(digit);
                    scored = true;
                }
            }
            if (k == '7' && kind3 == -1)
            {
                if (is_kind3()) kind3 = add_all();
                else kind3 = 0;
                scored = true;
            }
            if (k == '8' && kind4 == -1)
            {
                if (is_kind4()) kind4 = add_all();
                else kind4 = 0;
                scored = true;
            }
            if (k == 'f' && full == -1)
            {
                if (is_full()) full = 25;
                else full = 0;
                scored = true;
            }
            if (k == 's' && small == -1)
            {
                if (is_small()) small = 30;
                else small = 0;
                scored = true;
            }
            if (k == 'l' && large == -1)
            { 
                if (is_large()) large = 40;
                else large = 0;
                scored = true;
            }
            if (k == '9' && kind5 != 0)
            {
                if (is_kind5())
                {
                    if (kind5 == -1) kind5 = 50;
                    else extra_yahtzees += 100;
                }
                else kind5 = 0;
                scored = true;
            }
            if (k == '0' && chance == -1)
            {
                chance = add_all();
                scored = true;
            }
            if (k == 'r' && rerolls_left > 0)
            {
                Console.Write("\rnumber key to toggle, enter to finish\r");
                Console.CursorTop -= 3;
                select_reroll();
                rerolls_left--;
                got_input = true;
            }
            if (scored)
            {
                rerolls_left = max_rerolls;
                got_input = true;
            }
        }
    }
    if (!reroll_toggle.Contains(true))
    {
        // redraw scorecard and wait
        var old_pos = Console.GetCursorPosition();
        Console.SetCursorPosition(0, 0);
        score_card();
        Console.SetCursorPosition(old_pos.Left, old_pos.Top);
        if (singles[1] != -1 && singles[2] != -1 && singles[3] != -1 &&
            singles[4] != -1 && singles[5] != -1 && singles[6] != -1 &&
            kind3 != -1 && kind4 != -1 && full != -1 &&
            small != -1 && large != -1 && kind5 != -1 && chance != -1)
            break;
        Console.Write("\n\npress a key...");
        Console.ReadKey(true);
    }
}
Console.Write("\n\ngame over!");
int score = kind3 + kind4 + full + small + large + 
    kind5 + chance + extra_yahtzees;
for (int i = 1; i <= 6; i++)
    score += singles[i];
Console.Write("\ntotal score: " + score);
while (true) ;

void score_card()
{
    Console.Write(
        "1) ones            (add only ones)    " + singles[1] + " \n" +
        "2) twos            (add only twos)    " + singles[2] + " \n" +
        "3) threes        (add only threes)    " + singles[3] + " \n" +
        "4) fours          (add only fours)    " + singles[4] + " \n" +
        "5) fives          (add only fives)    " + singles[5] + " \n" +
        "6) sixes          (add only sixes)    " + singles[6] + " \n" +
        "7) 3 of a kind      (add all dice)    " + kind3 + " \n" +
        "8) 4 of a kind      (add all dice)    " + kind4 + " \n" +
        "f) full house          (25 points)    " + full + " \n" +
        "s) small straight 4    (30 points)    " + small + " \n" +
        "l) large straight 5    (40 points)    " + large + " \n" +
        "9) yahtzee (5kind)     (50 points)    " + kind5 + " \n" +
        "0) chance           (add all dice)    " + chance + " \n" +
        "   extra yahtzees     (100 points)    " + extra_yahtzees + " \n");
}

void roll_dice()
{
    if (reroll_toggle.Contains(true))
    {
        for (int i = 0; i < 5; i++)
            if (reroll_toggle[i])
                dice[i] = random.Next(6) + 1;
    }
    else
    {
        for (int i = 0; i < 5; i++)
            dice[i] = random.Next(6) + 1;
    }
}

int count_singles(int face)
{
    int total = 0;
    for (int i = 0; i < 5; i++)
        if (dice[i] == face) total += face;
    return total;
}

bool is_kind3()
{
    List<int> list = dice.ToList();
    list.Sort();
    int first = 2; // last 3
    if (list[0] == list[1]) first = 0; // first 3
    else if (list[1] == list[2]) first = 1; // middle 3
    int match = list[first];
    bool fail = false;
    for (int i = 0; i < 3; i++)
        if (list[first + i] != match) fail = true;
    return !fail;
}

bool is_kind4()
{
    List<int> list = dice.ToList();
    list.Sort();
    int first = 1; // last 4
    if (list[0] == list[1]) first = 0; // first 4
    int match = list[first];
    bool fail = false;
    for (int i = 0; i < 4; i++)
        if (list[first + i] != match) fail = true;
    return !fail;
}

bool is_kind5()
{
    int match = dice[0];
    bool fail = false;
    for (int i = 0; i < 5; i++)
        if (dice[i] != match) fail = true;
    return !fail;
}

bool is_full()
{
    List<int> list = dice.ToList();
    list.Sort();
    if (list[0] == list[1] && list[3] == list[4])
        if (list[2] == list[0] || list[2] == list[4])
            return true;
    return false;
}

bool is_small()
{
    // 1234 run
    bool fail = false;
    for (int i = 1; i <= 4; i++)
        if (!dice.Contains(i)) fail = true;
    if (!fail) return true;
    // 2345 run
    fail = false;
    for (int i = 2; i <= 5; i++)
        if (!dice.Contains(i)) fail = true;
    if (!fail) return true;
    // 3456 run
    fail = false;
    for (int i = 3; i <= 6; i++)
        if (!dice.Contains(i)) fail = true;
    if (!fail) return true;
    return false;
}

bool is_large()
{
    // 12345 run
    bool fail = false;
    for (int i = 1; i <= 5; i++)
        if (!dice.Contains(i)) fail = true;
    if (!fail) return true;
    // 23456 run
    fail = false;
    for (int i = 2; i <= 6; i++)
        if (!dice.Contains(i)) fail = true;
    if (!fail) return true;
    return false;
}

int add_all()
{
    int total = 0;
    for (int i = 0; i < 5; i++)
        total += dice[i];
    return total;
}

void select_reroll()
{
    reroll_toggle = new bool[] { false, false, false, false, false };
    while (true) // go until enter ('\r')
    {
        char k = ' ';
        while(true)
        {
            k = Console.ReadKey(true).KeyChar;
            if ("12345\r".Contains(k)) break; 
        }
        if (k == '\r') break;
        int i = k - '0' - 1;
        reroll_toggle[i] = !reroll_toggle[i];
        Console.Write("\r");
        for (i = 0; i < 5; i++)
        {
            if (reroll_toggle[i]) Console.Write("[*] ");
            else Console.Write("[" + dice[i] + "] ");
        }
    }
}