Import std.algo.combinatorics

Permutations

std.algo.combinatorics

function

Public Function Permutations<T>(items: T[]): PermutationIterator<T>

Every order of the array's elements: n! of them, from the array's own order. The array is copied, so changing it doesn't change them.

Examples

Local orders: Int[][] = []
For order In Permutations([1, 2, 3])
    orders.Add(order)
End For

Expect(orders.Count == 6)
Expect(orders[0] == [1, 2, 3] && orders[5] == [3, 2, 1])

std/algo/combinatorics.fb, line 155

function

@PanicsAtCaller Public Function Permutations<T>(items: T[], count: Int): PermutationIterator<T>

Every order of count of the array's elements: n! / (n - count)! of them, none when count is more than n, and one empty one for 0. The array is copied. A negative count panics.

Examples

Local pairs: String[][] = []
For pair In Permutations(["a", "b", "c"], 2)
    pairs.Add(pair)
End For

Expect(pairs == [["a", "b"], ["a", "c"], ["b", "a"], ["b", "c"], ["c", "a"], ["c", "b"]])

std/algo/combinatorics.fb, line 172

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