2018-10-10 22:03:03 +00:00
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id: 565bbe00e9cc8ac0725390f4
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2021-03-15 03:20:39 +00:00
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title: 21 点游戏
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2018-10-10 22:03:03 +00:00
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challengeType: 1
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2020-04-29 10:29:13 +00:00
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videoUrl: 'https://scrimba.com/c/c6KE7ty'
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forumTopicId: 16809
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2021-01-13 02:31:00 +00:00
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dashedName: counting-cards
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2018-10-10 22:03:03 +00:00
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---
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2020-12-16 07:37:30 +00:00
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# --description--
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2018-10-10 22:03:03 +00:00
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2021-03-15 03:20:39 +00:00
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在赌场 21 点游戏中,玩家可以通过计算牌桌上已经发放的卡牌的高低值来让自己在游戏中保持优势。 这就叫 [21 点算法](https://en.wikipedia.org/wiki/Card_counting)。
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2020-12-16 07:37:30 +00:00
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2021-03-15 03:20:39 +00:00
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牌桌上的大值的卡牌更多,对玩家有利。 根据下面的表格,每张卡牌都被分配了一个值。 如果卡牌的值大于 0,那么玩家应该追加赌注。 如果卡牌的值为 0 或负数,玩家应该追加少许赌注甚至不追加赌注。
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2020-12-16 07:37:30 +00:00
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2021-03-15 03:20:39 +00:00
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<table class='table table-striped'><thead><tr><th>计数</th><th>卡牌</th></tr></thead><tbody><tr><td>+1</td><td>2, 3, 4, 5, 6</td></tr><tr><td>0</td><td>7, 8, 9</td></tr><tr><td>-1</td><td>10, 'J', 'Q', 'K', 'A'</td></tr></tbody></table>
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2018-10-10 22:03:03 +00:00
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2021-03-15 03:20:39 +00:00
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请写一个函数实现 21 点算法。 它根据参数 `card` 的值(见表格,可能是数字或者字符串)来递增或递减全局变量 `count`。 然后函数返回一个由当前 count(计数)和 `Bet`(当 count > 0 时)或 `Hold`(当 count <= 0 时) 拼接的字符串。 注意 count(计数)和玩家的决定(`Bet` 或 `Hold`)之间应该有空格。
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2018-10-10 22:03:03 +00:00
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2021-04-05 15:04:04 +00:00
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**示例输出:**`-3 Hold` 或者 `5 Bet`
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2021-02-06 04:42:36 +00:00
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2021-03-15 03:20:39 +00:00
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**提示:**
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当卡牌为 7、8、9 时,不要把 `count` 值重置为 0。 不要返回一个数组。
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输出结果中不要包含单引号或双引号。
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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# --hints--
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2021-03-15 03:20:39 +00:00
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卡牌序列 2、3、4、5、6 应该返回 `5 Bet`
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2018-10-10 22:03:03 +00:00
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```js
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2020-12-16 07:37:30 +00:00
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assert(
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(function () {
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count = 0;
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cc(2);
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cc(3);
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cc(4);
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cc(5);
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var out = cc(6);
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if (out === '5 Bet') {
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return true;
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}
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return false;
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})()
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);
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```
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2018-10-10 22:03:03 +00:00
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2021-03-15 03:20:39 +00:00
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卡牌序列 7、8、9 应该返回 `0 Hold`
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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```js
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assert(
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(function () {
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count = 0;
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cc(7);
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cc(8);
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var out = cc(9);
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if (out === '0 Hold') {
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return true;
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}
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return false;
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})()
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);
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```
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2018-10-10 22:03:03 +00:00
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2021-03-15 03:20:39 +00:00
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卡牌序列 10、J、Q、K、A 应该返回 `-5 Hold`
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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```js
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assert(
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(function () {
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count = 0;
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cc(10);
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cc('J');
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cc('Q');
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cc('K');
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var out = cc('A');
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if (out === '-5 Hold') {
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return true;
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}
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return false;
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})()
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);
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2018-10-10 22:03:03 +00:00
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```
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2021-03-15 03:20:39 +00:00
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卡牌序列 3、7、Q、8、A 应该返回 `-1 Hold`
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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```js
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assert(
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(function () {
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count = 0;
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cc(3);
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cc(7);
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cc('Q');
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cc(8);
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var out = cc('A');
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if (out === '-1 Hold') {
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return true;
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}
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return false;
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})()
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);
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```
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2018-10-10 22:03:03 +00:00
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2021-03-15 03:20:39 +00:00
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卡牌序列 2、J、9、2、7 应该返回 `1 Bet`
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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```js
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assert(
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(function () {
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count = 0;
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cc(2);
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cc('J');
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cc(9);
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cc(2);
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var out = cc(7);
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if (out === '1 Bet') {
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return true;
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}
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return false;
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})()
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);
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```
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2018-10-10 22:03:03 +00:00
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2021-03-15 03:20:39 +00:00
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卡牌序列 2、2、10 应该返回 `1 Bet`
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2018-10-10 22:03:03 +00:00
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2020-12-16 07:37:30 +00:00
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```js
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assert(
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(function () {
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count = 0;
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cc(2);
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cc(2);
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var out = cc(10);
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if (out === '1 Bet') {
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return true;
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}
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return false;
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})()
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);
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```
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2021-03-15 03:20:39 +00:00
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卡牌序列 3、2、A、10、K 应该返回 `-1 Hold`
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2020-04-29 10:29:13 +00:00
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2018-10-10 22:03:03 +00:00
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```js
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2020-12-16 07:37:30 +00:00
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assert(
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(function () {
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count = 0;
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cc(3);
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cc(2);
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cc('A');
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cc(10);
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var out = cc('K');
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if (out === '-1 Hold') {
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return true;
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}
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return false;
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})()
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);
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2018-10-10 22:03:03 +00:00
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```
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2020-04-29 10:29:13 +00:00
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2021-01-13 02:31:00 +00:00
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# --seed--
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## --seed-contents--
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```js
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2021-10-27 15:10:57 +00:00
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let count = 0;
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2021-01-13 02:31:00 +00:00
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function cc(card) {
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// Only change code below this line
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return "Change Me";
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// Only change code above this line
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}
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cc(2); cc(3); cc(7); cc('K'); cc('A');
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```
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2020-12-16 07:37:30 +00:00
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# --solutions--
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2021-01-13 02:31:00 +00:00
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```js
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2021-10-27 15:10:57 +00:00
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let count = 0;
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2021-01-13 02:31:00 +00:00
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function cc(card) {
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switch(card) {
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case 2:
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case 3:
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case 4:
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case 5:
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case 6:
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count++;
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break;
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case 10:
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case 'J':
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case 'Q':
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case 'K':
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case 'A':
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count--;
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}
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if(count > 0) {
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return count + " Bet";
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} else {
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return count + " Hold";
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}
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}
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```
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