Cartesian product of two or more lists: Difference between revisions
Content added Content deleted
Alextretyak (talk | contribs) m (→{{header|11l}}) |
(Add Swift) |
||
Line 3,122:
6. | 3 5 6 1 |
+---------------------+</lang>
=={{header|Swift}}==
{{trans|Scala}}
<lang swift>func + <T>(el: T, arr: [T]) -> [T] {
var ret = arr
ret.insert(el, at: 0)
return ret
}
func cartesianProduct<T>(_ arrays: [T]...) -> [[T]] {
guard let head = arrays.first else {
return []
}
let first = Array(head)
func pel(
_ el: T,
_ ll: [[T]],
_ a: [[T]] = []
) -> [[T]] {
switch ll.count {
case 0:
return a.reversed()
case _:
let tail = Array(ll.dropFirst())
let head = ll.first!
return pel(el, tail, el + head + a)
}
}
return arrays.reversed()
.reduce([first], {res, el in el.flatMap({ pel($0, res) }) })
.map({ $0.dropLast(first.count) })
}
print(cartesianProduct([1, 2], [3, 4]))
print(cartesianProduct([3, 4], [1, 2]))
print(cartesianProduct([1, 2], []))
print(cartesianProduct([1776, 1789], [7, 12], [4, 14, 23], [0, 1]))
print(cartesianProduct([1, 2, 3], [30], [500, 100]))
print(cartesianProduct([1, 2, 3], [], [500, 100])</lang>
{{out}}
<pre>[[1, 3], [1, 4], [2, 3], [2, 4]]
[[3, 1], [3, 2], [4, 1], [4, 2]]
[]
[[1776, 7, 4, 0], [1776, 7, 4, 1], [1776, 7, 14, 0], [1776, 7, 14, 1], [1776, 7, 23, 0], [1776, 7, 23, 1], [1776, 12, 4, 0], [1776, 12, 4, 1], [1776, 12, 14, 0], [1776, 12, 14, 1], [1776, 12, 23, 0], [1776, 12, 23, 1], [1789, 7, 4, 0], [1789, 7, 4, 1], [1789, 7, 14, 0], [1789, 7, 14, 1], [1789, 7, 23, 0], [1789, 7, 23, 1], [1789, 12, 4, 0], [1789, 12, 4, 1], [1789, 12, 14, 0], [1789, 12, 14, 1], [1789, 12, 23, 0], [1789, 12, 23, 1]]
[[1, 30, 500], [1, 30, 100], [2, 30, 500], [2, 30, 100], [3, 30, 500], [3, 30, 100]]
[]</pre>
=={{header|Tcl}}==
| |||