mirror of
https://github.com/lynchmarkHQ/lynchmark.com.git
synced 2026-10-18 17:57:55 +00:00
41 lines
1.0 KiB
JavaScript
41 lines
1.0 KiB
JavaScript
const loadLodash = (() => {
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let p;
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return () =>
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p || (p = import("https://cdn.jsdelivr.net/npm/lodash@4.17.21/+esm")
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.then(m => m.default || m)
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.catch(e => (p = null, Promise.reject(e))));
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})();
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async function findConvexHull(points) {
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const _ = await loadLodash();
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if (!Array.isArray(points)) throw new TypeError("Expected an array of points");
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const pts = _.uniqBy(
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points.filter(p => p && Number.isFinite(p.x) && Number.isFinite(p.y)),
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p => `${p.x}|${p.y}`
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);
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if (pts.length < 2) return pts.slice();
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const s = _.sortBy(pts, ["x", "y"]);
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const cross = (o, a, b) =>
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(a.x - o.x) * (b.y - o.y) - (a.y - o.y) * (b.x - o.x);
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const build = arr => {
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const h = [];
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for (const p of arr) {
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while (h.length > 1 && cross(h[h.length - 2], h[h.length - 1], p) <= 0) h.pop();
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h.push(p);
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}
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return h;
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};
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const lo = build(s);
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const up = build(s.slice().reverse());
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lo.pop();
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up.pop();
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return lo.concat(up);
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}
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export default findConvexHull;
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// Generation time: 134.929s
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// Result: PASS
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