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Generalized solution to creating k-sized sub/supersets from a given set
Reporting duplicate entry for a given set of dataLet's play some Swift PokerFrom scratch pub sub definition and implementationPoker app in C#Finding permutation from given lexicographical rankFind the nearest point of a given set of pointsFaster way to loop through array of points and find if within polygonsCreating a array of custom objects from JSON, sent using PHP from a MySQL databaseCounting contiguous subarrays with a negative sumIncrease performance creating Mandelbrot set in python
.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty margin-bottom:0;
$begingroup$
In this code for a Set Game, using nested for-loops seems inevitable. But suppose there were more properties to provide for the Card initializer, the pyramid of nested loops would grow even bigger.
A possible solution could be to generate all the possible k-sized sub/supersets from the initial set, and then loop through them:
func combinations<C: Collection>(sized k: Int, from collection: C) -> [[C.Element]]
var result: [[C.Element]] = [[]]
var lastCount = 1
while result[result.count - 1].count < k
for i in result.indices.suffix(lastCount)
for element in collection
result.append(result[i] + [element])
lastCount *= collection.count
return Array(result.suffix(lastCount))
A deck of cards would be created like so:
struct Card
let number: Int
let symbol: Int
let color: Int
let shading: Int
var deck: [Card] = combinations(sized: 4, from: 1..<3)
.map Card(number : $0[0],
symbol : $0[1],
color : $0[2],
shading : $0[3])
The advantage of this approach is that it could be used to concoct subsets as well as supersets :
for comb in combinations(sized: 5, from: ["a", "b", "c"])
print(comb.joined()) //"aaaaa", "aaaab", ... , "ccccc"
//Or if you're feeling artsy
combinations(sized: 2, from: [UIColor.red, UIColor.green, UIColor.blue])
The one limitation is that it quickly goes slow for higher k or collection.count since this is an O(nk) algorithm I believe (n being the collection count). Is there a better way?
Feedback on all aspects of the code is welcome, such as (but not limited to):
- Efficiency,
- Readability,
- Naming.
performance swift
$endgroup$
add a comment |
$begingroup$
In this code for a Set Game, using nested for-loops seems inevitable. But suppose there were more properties to provide for the Card initializer, the pyramid of nested loops would grow even bigger.
A possible solution could be to generate all the possible k-sized sub/supersets from the initial set, and then loop through them:
func combinations<C: Collection>(sized k: Int, from collection: C) -> [[C.Element]]
var result: [[C.Element]] = [[]]
var lastCount = 1
while result[result.count - 1].count < k
for i in result.indices.suffix(lastCount)
for element in collection
result.append(result[i] + [element])
lastCount *= collection.count
return Array(result.suffix(lastCount))
A deck of cards would be created like so:
struct Card
let number: Int
let symbol: Int
let color: Int
let shading: Int
var deck: [Card] = combinations(sized: 4, from: 1..<3)
.map Card(number : $0[0],
symbol : $0[1],
color : $0[2],
shading : $0[3])
The advantage of this approach is that it could be used to concoct subsets as well as supersets :
for comb in combinations(sized: 5, from: ["a", "b", "c"])
print(comb.joined()) //"aaaaa", "aaaab", ... , "ccccc"
//Or if you're feeling artsy
combinations(sized: 2, from: [UIColor.red, UIColor.green, UIColor.blue])
The one limitation is that it quickly goes slow for higher k or collection.count since this is an O(nk) algorithm I believe (n being the collection count). Is there a better way?
Feedback on all aspects of the code is welcome, such as (but not limited to):
- Efficiency,
- Readability,
- Naming.
performance swift
$endgroup$
add a comment |
$begingroup$
In this code for a Set Game, using nested for-loops seems inevitable. But suppose there were more properties to provide for the Card initializer, the pyramid of nested loops would grow even bigger.
A possible solution could be to generate all the possible k-sized sub/supersets from the initial set, and then loop through them:
func combinations<C: Collection>(sized k: Int, from collection: C) -> [[C.Element]]
var result: [[C.Element]] = [[]]
var lastCount = 1
while result[result.count - 1].count < k
for i in result.indices.suffix(lastCount)
for element in collection
result.append(result[i] + [element])
lastCount *= collection.count
return Array(result.suffix(lastCount))
A deck of cards would be created like so:
struct Card
let number: Int
let symbol: Int
let color: Int
let shading: Int
var deck: [Card] = combinations(sized: 4, from: 1..<3)
.map Card(number : $0[0],
symbol : $0[1],
color : $0[2],
shading : $0[3])
The advantage of this approach is that it could be used to concoct subsets as well as supersets :
for comb in combinations(sized: 5, from: ["a", "b", "c"])
print(comb.joined()) //"aaaaa", "aaaab", ... , "ccccc"
//Or if you're feeling artsy
combinations(sized: 2, from: [UIColor.red, UIColor.green, UIColor.blue])
The one limitation is that it quickly goes slow for higher k or collection.count since this is an O(nk) algorithm I believe (n being the collection count). Is there a better way?
Feedback on all aspects of the code is welcome, such as (but not limited to):
- Efficiency,
- Readability,
- Naming.
performance swift
$endgroup$
In this code for a Set Game, using nested for-loops seems inevitable. But suppose there were more properties to provide for the Card initializer, the pyramid of nested loops would grow even bigger.
A possible solution could be to generate all the possible k-sized sub/supersets from the initial set, and then loop through them:
func combinations<C: Collection>(sized k: Int, from collection: C) -> [[C.Element]]
var result: [[C.Element]] = [[]]
var lastCount = 1
while result[result.count - 1].count < k
for i in result.indices.suffix(lastCount)
for element in collection
result.append(result[i] + [element])
lastCount *= collection.count
return Array(result.suffix(lastCount))
A deck of cards would be created like so:
struct Card
let number: Int
let symbol: Int
let color: Int
let shading: Int
var deck: [Card] = combinations(sized: 4, from: 1..<3)
.map Card(number : $0[0],
symbol : $0[1],
color : $0[2],
shading : $0[3])
The advantage of this approach is that it could be used to concoct subsets as well as supersets :
for comb in combinations(sized: 5, from: ["a", "b", "c"])
print(comb.joined()) //"aaaaa", "aaaab", ... , "ccccc"
//Or if you're feeling artsy
combinations(sized: 2, from: [UIColor.red, UIColor.green, UIColor.blue])
The one limitation is that it quickly goes slow for higher k or collection.count since this is an O(nk) algorithm I believe (n being the collection count). Is there a better way?
Feedback on all aspects of the code is welcome, such as (but not limited to):
- Efficiency,
- Readability,
- Naming.
performance swift
performance swift
edited 20 mins ago
ielyamani
asked 26 mins ago
ielyamaniielyamani
372213
372213
add a comment |
add a comment |
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