409c39abf1
* feat(curriculum): Add Basic JS Scrimba links * Fix: Add missing video url. * fix: update videoUrl
105 lines
4.4 KiB
Markdown
105 lines
4.4 KiB
Markdown
---
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id: 565bbe00e9cc8ac0725390f4
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title: Counting Cards
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challengeType: 1
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videoUrl: 'https://scrimba.com/c/c6KE7ty'
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---
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## Description
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<section id='description'>
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In the casino game Blackjack, a player can gain an advantage over the house by keeping track of the relative number of high and low cards remaining in the deck. This is called <a href='https://en.wikipedia.org/wiki/Card_counting' target='_blank'>Card Counting</a>.
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Having more high cards remaining in the deck favors the player. Each card is assigned a value according to the table below. When the count is positive, the player should bet high. When the count is zero or negative, the player should bet low.
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<table class="table table-striped"><thead><tr><th>Count Change</th><th>Cards</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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You will write a card counting function. It will receive a <code>card</code> parameter, which can be a number or a string, and increment or decrement the global <code>count</code> variable according to the card's value (see table). The function will then return a string with the current count and the string <code>Bet</code> if the count is positive, or <code>Hold</code> if the count is zero or negative. The current count and the player's decision (<code>Bet</code> or <code>Hold</code>) should be separated by a single space.
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<strong>Example Output</strong><br><code>-3 Hold</code><br><code>5 Bet</code>
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<strong>Hint</strong><br>Do NOT reset <code>count</code> to 0 when value is 7, 8, or 9.<br>Do NOT return an array.<br>Do NOT include quotes (single or double) in the output.
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</section>
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## Instructions
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<section id='instructions'>
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</section>
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## Tests
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<section id='tests'>
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```yml
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tests:
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- text: Cards Sequence 2, 3, 4, 5, 6 should return <code>5 Bet</code>
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testString: assert((function(){ count = 0; cc(2);cc(3);cc(4);cc(5);var out = cc(6); if(out === "5 Bet") {return true;} return false; })(), 'Cards Sequence 2, 3, 4, 5, 6 should return <code>5 Bet</code>');
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- text: Cards Sequence 7, 8, 9 should return <code>0 Hold</code>
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testString: assert((function(){ count = 0; cc(7);cc(8);var out = cc(9); if(out === "0 Hold") {return true;} return false; })(), 'Cards Sequence 7, 8, 9 should return <code>0 Hold</code>');
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- text: Cards Sequence 10, J, Q, K, A should return <code>-5 Hold</code>
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testString: assert((function(){ count = 0; cc(10);cc('J');cc('Q');cc('K');var out = cc('A'); if(out === "-5 Hold") {return true;} return false; })(), 'Cards Sequence 10, J, Q, K, A should return <code>-5 Hold</code>');
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- text: Cards Sequence 3, 7, Q, 8, A should return <code>-1 Hold</code>
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testString: assert((function(){ count = 0; cc(3);cc(7);cc('Q');cc(8);var out = cc('A'); if(out === "-1 Hold") {return true;} return false; })(), 'Cards Sequence 3, 7, Q, 8, A should return <code>-1 Hold</code>');
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- text: Cards Sequence 2, J, 9, 2, 7 should return <code>1 Bet</code>
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testString: assert((function(){ count = 0; cc(2);cc('J');cc(9);cc(2);var out = cc(7); if(out === "1 Bet") {return true;} return false; })(), 'Cards Sequence 2, J, 9, 2, 7 should return <code>1 Bet</code>');
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- text: Cards Sequence 2, 2, 10 should return <code>1 Bet</code>
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testString: assert((function(){ count = 0; cc(2);cc(2);var out = cc(10); if(out === "1 Bet") {return true;} return false; })(), 'Cards Sequence 2, 2, 10 should return <code>1 Bet</code>');
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- text: Cards Sequence 3, 2, A, 10, K should return <code>-1 Hold</code>
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testString: assert((function(){ count = 0; cc(3);cc(2);cc('A');cc(10);var out = cc('K'); if(out === "-1 Hold") {return true;} return false; })(), 'Cards Sequence 3, 2, A, 10, K should return <code>-1 Hold</code>');
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```
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</section>
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## Challenge Seed
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<section id='challengeSeed'>
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<div id='js-seed'>
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```js
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var count = 0;
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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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// Add/remove calls to test your function.
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// Note: Only the last will display
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cc(2); cc(3); cc(7); cc('K'); cc('A');
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```
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</div>
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</section>
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## Solution
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<section id='solution'>
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```js
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var count = 0;
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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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</section>
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