* fix: Format challenge markdown according to linting rules * fix: Put spaces after section tags
		
			
				
	
	
		
			101 lines
		
	
	
		
			2.4 KiB
		
	
	
	
		
			Markdown
		
	
	
	
	
	
			
		
		
	
	
			101 lines
		
	
	
		
			2.4 KiB
		
	
	
	
		
			Markdown
		
	
	
	
	
	
---
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title: SEDOLs
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id: 59d9c6bc214c613ba73ff012
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challengeType: 5
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---
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## Description
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<section id='description'>
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For each number list of 6-digit <a href="https://en.wikipedia.org/wiki/SEDOL" title="wp: SEDOL" target="_blank">SEDOL</a>s, calculate and append the checksum digit.
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That is, given the input string on the left, your function should return the corresponding string on the right:
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<pre>
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710889 => 7108899
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B0YBKJ => B0YBKJ7
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406566 => 4065663
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B0YBLH => B0YBLH2
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228276 => 2282765
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B0YBKL => B0YBKL9
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557910 => 5579107
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B0YBKR => B0YBKR5
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585284 => 5852842
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B0YBKT => B0YBKT7
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B00030 => B000300
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</pre>
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Check that each input is correctly formed, especially with respect to valid characters allowed in a SEDOL string. Your function should return <code>null</code> on an invalid input.
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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: <code>sedol</code> is a function.
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    testString: assert(typeof sedol === 'function', '<code>sedol</code> is a function.');
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  - text: <code>sedol('a')</code> should return null.
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    testString: assert(sedol('a') === null, "<code>sedol('a')</code> should return null.");
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  - text: <code>sedol('710889')</code> should return '7108899'.
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    testString: assert(sedol('710889') === '7108899', "<code>sedol('710889')</code> should return '7108899'.");
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  - text: <code>sedol('BOATER')</code> should return null.
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    testString: assert(sedol('BOATER') === null, "<code>sedol('BOATER')</code> should return null.");
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  - text: <code>sedol('228276')</code> should return '2282765'.
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    testString: assert(sedol('228276') === '2282765', "<code>sedol('228276')</code> should return '2282765'.");
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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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function sedol(input) {
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  // Good luck!
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  return true;
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}
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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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function sedol(input) {
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  const checkDigit = sedolCheckDigit(input);
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  if (checkDigit !== null) {
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    return input + checkDigit;
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  }
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  return null;
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}
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const weight = [1, 3, 1, 7, 3, 9, 1];
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function sedolCheckDigit(char6) {
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  if (char6.search(/^[0-9BCDFGHJKLMNPQRSTVWXYZ]{6}$/) === -1) {
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    return null;
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  }
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  let sum = 0;
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  for (let i = 0; i < char6.length; i++) {
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    sum += weight[i] * parseInt(char6.charAt(i), 36);
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  }
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  const check = (10 - (sum % 10)) % 10;
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  return check.toString();
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}
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```
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</section>
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