Instance Methodswift-algorithms 1.2.1Algorithms->Swift

    uniquePermutations(ofCount:)

    Returns a sequence of the unique permutations of this sequence of the specified length.

    Permutations.swift:547
    func uniquePermutations(ofCount k: Int? = nil) -> UniquePermutationsSequence<Self>
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    FNV24 hash
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    Constraints
    where Self.Element:Hashable

    Parameters

    k

    The number of elements to include in each permutation. If k is nil, the resulting sequence represents permutations of this entire collection. If k is greater than the number of elements in this collection, the resulting sequence is empty.

    Use this method to iterate over the unique permutations of a sequence with repeating elements. This example prints every unique two-element permutation of an array of numbers:

    let numbers = [1, 1, 2]
for perm in numbers.uniquePermutations(ofCount: 2) {
    print(perm)
}
// [1, 1]
// [1, 2]
// [2, 1]

    By contrast, the permutations(ofCount:) method permutes a collection’s elements by position, and can include permutations with equal elements in each permutation:

    for perm in numbers.permutations(ofCount: 2)
    print(perm)
}
// [1, 1]
// [1, 1]
// [1, 2]
// [1, 2]
// [2, 1]
// [2, 1]

    The returned permutations are in lexicographically sorted order.