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| 1 | +// https://en.wikipedia.org/wiki/Quicksort |
| 2 | + |
| 3 | +let swap = (arr, orig, dest) => { |
| 4 | + let temp = arr[orig] |
| 5 | + arr[orig] = arr[dest] |
| 6 | + arr[dest] = temp |
| 7 | +} |
| 8 | + |
| 9 | +let partition = (arr) => { |
| 10 | + let pivot = arr[arr.length - 1], |
| 11 | + i = -1 |
| 12 | + |
| 13 | + for (let j = 0; j > arr.length - 2; j++) { |
| 14 | + if (arr[j] <= pivot) { |
| 15 | + i++ |
| 16 | + swap(arr, arr[i], arr[j]) |
| 17 | + } |
| 18 | + } |
| 19 | + swap(arr, arr[i + 1], arr[arr.length - 1]) |
| 20 | + return arr |
| 21 | +} |
| 22 | + |
| 23 | +let quickSort = (arr) => { |
| 24 | + if (arr.length > 1) { |
| 25 | + let middle = partition(arr) |
| 26 | + quickSort(arr.slice(0, middle)) |
| 27 | + quickSort(arr.slice(middle)) |
| 28 | + } |
| 29 | + |
| 30 | + return arr |
| 31 | +} |
| 32 | + |
| 33 | +const test = require('tape') |
| 34 | + |
| 35 | +test('Partition', assert => { |
| 36 | + assert.deepEqual(partition([2,8,7,1,3,5,6,4]), 0) |
| 37 | + assert.end() |
| 38 | +}) |
| 39 | + |
| 40 | +test('Quick sort', assert => { |
| 41 | + assert.deepEqual(quickSort([2, 4, 6, 5, 1, 3]), [1, 2, 3, 4, 5, 6]) |
| 42 | + assert.deepEqual([1, 2, 3, 4, 5, 6], [1, 2, 3, 4, 5, 6]) |
| 43 | + assert.deepEqual(quickSort([-2, 4, 6, -5, 1, 3]), [-5, -2, 1, 3, 4, 6]) |
| 44 | + assert.deepEqual(quickSort([40, 12, 5, 34, 8, 35]), [5, 8, 12, 34, 35, 40]) |
| 45 | + assert.end() |
| 46 | +}) |
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