31 lines
968 B
Markdown
31 lines
968 B
Markdown
---
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title: mergeSort
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tags: algorithm,array,recursion,advanced
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---
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Sorts an array of numbers, using the merge sort algorithm.
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- Use recursion.
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- If the `length` of the array is less than `2`, return the array.
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- Use `Math.floor()` to calculate the middle point of the array.
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- Use `Array.prototype.slice()` to slice the array in two and recursively call `mergeSort()` on the created subarrays.
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- Finally, use `Array.from()` and `Array.prototype.shift()` to combine the two sorted subarrays into one.
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```js
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const mergeSort = arr => {
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if (arr.length < 2) return arr;
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const mid = Math.floor(arr.length / 2);
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const l = mergeSort(arr.slice(0, mid));
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const r = mergeSort(arr.slice(mid, arr.length));
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return Array.from({ length: l.length + r.length }, () => {
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if (!l.length) return r.shift();
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else if (!r.length) return l.shift();
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else return l[0] > r[0] ? r.shift() : l.shift();
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});
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};
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```
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```js
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mergeSort([5, 1, 4, 2, 3]); // [1, 2, 3, 4, 5]
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```
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