nthperm(p)

Return the k that generated permutation p. Note that nthperm(nthperm([1:n], k)) == k for 1 <= k <= factorial(n).

Examples

In the Julia programming language, the function nthperm(v, k) computes the kth lexicographic permutation of a vector v.

julia> nthperm([1, 2, 3], 2)
3-element Array{Int64,1}:
 1
 3
 2

Here are some common examples of its use:

Generate the first lexicographic permutation:
```
julia> nthperm([4, 2, 3], 1)
3-element Array{Int64,1}:
4
2
3
```
This example generates the first lexicographic permutation of the vector [4, 2, 3].
Find the 5th lexicographic permutation:
```
julia> nthperm([1, 2, 3], 5)
3-element Array{Int64,1}:
2
3
1
```
It computes the 5th lexicographic permutation of the vector [1, 2, 3].
Compute a permutation of a string:
```
julia> nthperm("abc", 2)
3-element Array{Char,1}:
'a'
'c'
'b'
```
This example demonstrates how nthperm works with a string input.

Common mistake example:

julia> nthperm([1, 2, 3], 7)
ERROR: ArgumentError: k (7) is greater than the number of permutations (6)

In this example, the value of k provided is greater than the total number of possible permutations for the given vector. It's important to ensure that k is within the valid range of permutations for the vector v to avoid such errors.

User Contributed Notes

Add a Note

The format of note supported is markdown, use triple backtick to start and end a code block.

nthperm(p)

Examples

See Also

User Contributed Notes

Add a Note