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18 lines
770 B
JavaScript
18 lines
770 B
JavaScript
async function findConvexHull(points) {
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const {sortBy, uniqWith} = await import('https://cdn.jsdelivr.net/npm/lodash-es@4.17.21/lodash.js')
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const ps = uniqWith(sortBy(points.map(({x, y}) => ({x: +x, y: +y})), ['x', 'y']), (a, b) => a.x === b.x && a.y === b.y)
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if (ps.length < 2) return ps
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const c = (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 (const p of ps) {
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while (lower.length > 1 && c(lower.at(-2), lower.at(-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 (const p of [...ps].reverse()) {
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while (upper.length > 1 && c(upper.at(-2), upper.at(-1), p) <= 0) upper.pop()
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upper.push(p)
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}
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return lower.slice(0, -1).concat(upper.slice(0, -1))
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}
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export default findConvexHull; |