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22 lines
688 B
JavaScript
22 lines
688 B
JavaScript
const findConvexHull = async (pts) => {
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const { default: _ } = await import('https://cdn.jsdelivr.net/npm/lodash@4.17.21/+esm')
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const s = _.sortBy(_.uniqWith(pts, _.isEqual), ['x', 'y'])
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if (s.length < 3) return s
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const k = (a, b, o) => (a.x - o.x) * (b.y - o.y) - (a.y - o.y) * (b.x - o.x)
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const build = (list) => {
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const stack = []
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for (const p of list) {
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while (stack.length > 1 && k(stack[stack.length - 1], p, stack[stack.length - 2]) <= 0) {
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stack.pop()
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}
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stack.push(p)
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}
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return stack
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}
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const l = build(s)
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const u = build([...s].reverse())
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return [...l.slice(0, -1), ...u.slice(0, -1)]
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}
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export default findConvexHull; |