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feat: use quickselect 3.0, remove ts-node dev dependency
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,12 @@ | ||
| /** | ||
| * Rearranges items so that all items in the [left, k] are the smallest. | ||
| * The k-th element will have the (k - left + 1)-th smallest value in [left, right]. | ||
| * | ||
| * @template T | ||
| * @param {T[]} arr the array to partially sort (in place) | ||
| * @param {number} k middle index for partial sorting (as defined above) | ||
| * @param {number} [left=0] left index of the range to sort | ||
| * @param {number} [right=arr.length-1] right index | ||
| * @param {(a: T, b: T) => number} [compare = (a, b) => a - b] compare function | ||
| */ | ||
| export default function quickselect<T>(arr: T[], k: number, left?: number | undefined, right?: number | undefined, compare?: ((a: T, b: T) => number) | undefined): void; |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,74 @@ | ||
| "use strict"; | ||
| Object.defineProperty(exports, "__esModule", { value: true }); | ||
| exports.default = quickselect; | ||
| /** | ||
| * Rearranges items so that all items in the [left, k] are the smallest. | ||
| * The k-th element will have the (k - left + 1)-th smallest value in [left, right]. | ||
| * | ||
| * @template T | ||
| * @param {T[]} arr the array to partially sort (in place) | ||
| * @param {number} k middle index for partial sorting (as defined above) | ||
| * @param {number} [left=0] left index of the range to sort | ||
| * @param {number} [right=arr.length-1] right index | ||
| * @param {(a: T, b: T) => number} [compare = (a, b) => a - b] compare function | ||
| */ | ||
| function quickselect(arr, k, left = 0, right = arr.length - 1, compare = defaultCompare) { | ||
| while (right > left) { | ||
| if (right - left > 600) { | ||
| const n = right - left + 1; | ||
| const m = k - left + 1; | ||
| const z = Math.log(n); | ||
| const s = 0.5 * Math.exp(2 * z / 3); | ||
| const sd = 0.5 * Math.sqrt(z * s * (n - s) / n) * (m - n / 2 < 0 ? -1 : 1); | ||
| const newLeft = Math.max(left, Math.floor(k - m * s / n + sd)); | ||
| const newRight = Math.min(right, Math.floor(k + (n - m) * s / n + sd)); | ||
| quickselect(arr, k, newLeft, newRight, compare); | ||
| } | ||
| const t = arr[k]; | ||
| let i = left; | ||
| /** @type {number} */ | ||
| let j = right; | ||
| swap(arr, left, k); | ||
| if (compare(arr[right], t) > 0) | ||
| swap(arr, left, right); | ||
| while (i < j) { | ||
| swap(arr, i, j); | ||
| i++; | ||
| j--; | ||
| while (compare(arr[i], t) < 0) | ||
| i++; | ||
| while (compare(arr[j], t) > 0) | ||
| j--; | ||
| } | ||
| if (compare(arr[left], t) === 0) | ||
| swap(arr, left, j); | ||
| else { | ||
| j++; | ||
| swap(arr, j, right); | ||
| } | ||
| if (j <= k) | ||
| left = j + 1; | ||
| if (k <= j) | ||
| right = j - 1; | ||
| } | ||
| } | ||
| /** | ||
| * @template T | ||
| * @param {T[]} arr | ||
| * @param {number} i | ||
| * @param {number} j | ||
| */ | ||
| function swap(arr, i, j) { | ||
| const tmp = arr[i]; | ||
| arr[i] = arr[j]; | ||
| arr[j] = tmp; | ||
| } | ||
| /** | ||
| * @template T | ||
| * @param {T} a | ||
| * @param {T} b | ||
| * @returns {number} | ||
| */ | ||
| function defaultCompare(a, b) { | ||
| return a < b ? -1 : a > b ? 1 : 0; | ||
| } |
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