Calculate all permutations of a string in Swift

Question

For the string \"ABC\" the code snippet below calculates 5 of the 6 total permutations. My strategy was to insert each character at each index possible index. B

Answer 1

You can use the functions of this framework to calculate permutations and combinations both with repetition and without repetition. You can investigate the source code and compare with your own.

https://github.com/amirrezaeghtedari/AECounting

This library calculates the results based on lexicographic order. For example the result of permutation 3 items out of 5 items are same as below:

let result = Permutation.permute(n: 5, r: 3)

//result
//[
// [1, 2, 3],
// [1, 2, 4],
// [1, 2, 5],
//  ...,
// 5, 4, 3]
//].

You can easily assign your problem items to 1 to n numbers in the result array.

In case of your problem, you should call:

let result = Permutation.permute(n: 3, r: 3)