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40 lines
1.1 KiB
JavaScript
40 lines
1.1 KiB
JavaScript
async function findConvexHull(points = []) {
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if (!Array.isArray(points)) throw new TypeError("Expected an array of points");
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const { sortBy, uniqBy } = await import("https://cdn.jsdelivr.net/npm/lodash-es@4.17.21/lodash.js");
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const pts = uniqBy(
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sortBy(
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points.filter(p => p && Number.isFinite(p.x) && Number.isFinite(p.y)),
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["x", "y"]
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),
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p => `${p.x},${p.y}`
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);
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const n = pts.length;
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if (n < 2) return pts.slice();
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const cross = (o, a, b) => (a.x - o.x) * (b.y - o.y) - (a.y - o.y) * (b.x - o.x);
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const lower = [];
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for (let i = 0; i < n; i++) {
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const p = pts[i];
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while (lower.length > 1 && cross(lower[lower.length - 2], lower[lower.length - 1], p) <= 0) lower.pop();
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lower.push(p);
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}
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const upper = [];
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for (let i = n - 1; i >= 0; i--) {
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const p = pts[i];
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while (upper.length > 1 && cross(upper[upper.length - 2], upper[upper.length - 1], p) <= 0) upper.pop();
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upper.push(p);
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}
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lower.pop();
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upper.pop();
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return lower.concat(upper);
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}
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export default findConvexHull;
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// Generation time: 16.419s
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// Result: PASS
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