8ee50178f3
Correct: `Array.from()` (it’s a static method) Incorrect: `Array.join()` (doesn’t exist; it’s a prototype method) This patch uses the common `#` syntax to denote `.prototype.`.
28 lines
1.0 KiB
Markdown
28 lines
1.0 KiB
Markdown
### stringPermutations
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⚠️ **WARNING**: This function's execution time increases exponentially with each character. Anything more than 8 to 10 characters will cause your browser to hang as it tries to solve all the different combinations.
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Generates all permutations of a string (contains duplicates).
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Use recursion.
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For each letter in the given string, create all the partial permutations for the rest of its letters.
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Use `Array.prototype.map()` to combine the letter with each partial permutation, then `Array.prototype.reduce()` to combine all permutations in one array.
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Base cases are for string `length` equal to `2` or `1`.
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```js
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const stringPermutations = str => {
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if (str.length <= 2) return str.length === 2 ? [str, str[1] + str[0]] : [str];
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return str
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.split('')
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.reduce(
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(acc, letter, i) =>
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acc.concat(stringPermutations(str.slice(0, i) + str.slice(i + 1)).map(val => letter + val)),
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[]
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);
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};
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```
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```js
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stringPermutations('abc'); // ['abc','acb','bac','bca','cab','cba']
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```
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