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Improved intersection #13

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Improved intersection #13

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da7f0f1
Improved intersection
psy-man Jan 16, 2018
dcdd2e7
Simplified algorithm
psy-man Jan 18, 2018
4a0fdb3
Intersection: Added test for checking duplicates
psy-man Jan 20, 2018
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19 changes: 10 additions & 9 deletions coding-intermediate/intersection.js
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Original file line number Diff line number Diff line change
Expand Up @@ -9,18 +9,18 @@ function intersection(left, right) {
// if we didn't use this object, we'd have to check
// if result contains current on every turn of the
// loop, which would take up to O(N * log(N)) time.
let seen = left.reduce((seen, item) => {
seen[item] = true
return seen
}, {})
//
// "new Set()" doesn't allow duplicates
const seen = new Set(left)

return right.reduce((result, current) => {
if (current in seen) {
return result.concat(current)
const result = right.reduce((result, num) => {
if (seen.has(num)) {
return result.add(num)
}
seen[current] = true
return result
}, [])
}, new Set())

return Array.from(result)
}

/// tests
Expand All @@ -29,3 +29,4 @@ import { test } from 'ava'

test(t => t.deepEqual(intersection([1, 5, 4, 2], [8, 91, 4, 1, 3]), [4, 1]))
test(t => t.deepEqual(intersection([1, 5, 4, 2], [7, 12]), []))
test(t => t.deepEqual(intersection([1, 5, 1, 10], [5, 1, 5, 12]), [5, 1]))