43 lines
951 B
Markdown
43 lines
951 B
Markdown
# Sorting
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**Task:** "Sort this array of numbers."
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## Without Ponytail
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```js
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function quickSort(arr, compareFn = (a, b) => a - b) {
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if (arr.length <= 1) return arr;
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const pivot = arr[Math.floor(arr.length / 2)];
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const left = [];
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const right = [];
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const equal = [];
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for (const item of arr) {
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const cmp = compareFn(item, pivot);
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if (cmp < 0) left.push(item);
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else if (cmp > 0) right.push(item);
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else equal.push(item);
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}
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return [
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...quickSort(left, compareFn),
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...equal,
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...quickSort(right, compareFn),
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];
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}
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const sorted = quickSort(numbers);
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```
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A hand-rolled quicksort. It allocates three arrays per recursion level, blows the stack on large inputs, and replaces an engine-optimized native sort with homework.
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## With Ponytail
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```js
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// ponytail: this exists
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numbers.sort((a, b) => a - b)
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```
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**24 lines → 1 line.** Every runtime ships a sort tuned by people whose whole job is sorting. Use it.
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