80 lines
1.7 KiB
Markdown
80 lines
1.7 KiB
Markdown
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---
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id: 596fda99c69f779975a1b67d
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title: Count occurrences of a substring
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challengeType: 5
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forumTopicId: 302237
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dashedName: count-occurrences-of-a-substring
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---
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# --description--
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Create a function, or show a built-in function, to count the number of non-overlapping occurrences of a substring inside a string.
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The function should take two arguments:
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<ul>
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<li>the first argument being the string to search, and</li>
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<li>the second a substring to be searched for.</li>
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</ul>
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It should return an integer count.
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The matching should yield the highest number of non-overlapping matches.
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In general, this essentially means matching from left-to-right or right-to-left.
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# --hints--
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`countSubstring` should be a function.
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```js
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assert(typeof countSubstring === 'function');
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```
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`countSubstring("the three truths", "th")` should return `3`.
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```js
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assert.equal(countSubstring(testCases[0], searchString[0]), results[0]);
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```
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`countSubstring("ababababab", "abab")` should return `2`.
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```js
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assert.equal(countSubstring(testCases[1], searchString[1]), results[1]);
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```
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`countSubstring("abaabba*bbaba*bbab", "a*b")` should return `2`.
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```js
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assert.equal(countSubstring(testCases[2], searchString[2]), results[2]);
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```
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# --seed--
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## --after-user-code--
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```js
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const testCases = ['the three truths', 'ababababab', 'abaabba*bbaba*bbab'];
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const searchString = ['th', 'abab', 'a*b'];
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const results = [3, 2, 2];
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```
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## --seed-contents--
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```js
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function countSubstring(str, subStr) {
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return true;
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}
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```
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# --solutions--
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```js
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function countSubstring(str, subStr) {
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const escapedSubStr = subStr.replace(/[.+*?^$[\]{}()|/]/g, '\\$&');
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const matches = str.match(new RegExp(escapedSubStr, 'g'));
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return matches ? matches.length : 0;
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}
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```
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