Algorithm to find next greater permutation of a given string

Question

I want an efficient algorithm to find the next greater permutation of the given string.

Answer 1

Wikipedia has a nice article on lexicographical order generation. It also describes an algorithm to generate the next permutation.

Quoting:

The following algorithm generates the next permutation lexicographically after a given permutation. It changes the given permutation in-place.

1. Find the highest index i such that s[i] < s[i+1]. If no such index exists, the permutation is the last permutation.
2. Find the highest index j > i such that s[j] > s[i]. Such a j must exist, since i+1 is such an index.
3. Swap s[i] with s[j].
4. Reverse the order of all of the elements after index i till the last element.

Answer 2

A great solution that works is described here: https://www.nayuki.io/page/next-lexicographical-permutation-algorithm. And the solution that, if next permutation exists, returns it, otherwise returns false:

function nextPermutation(array) {     var i = array.length - 1;     while (i > 0 && array[i - 1] >= array[i]) {         i--;     }      if (i <= 0) {         return false;     }      var j = array.length - 1;      while (array[j] <= array[i - 1]) {         j--;     }      var temp = array[i - 1];     array[i - 1] = array[j];     array[j] = temp;      j = array.length - 1;      while (i < j) {         temp = array[i];         array[i] = array[j];         array[j] = temp;         i++;         j--;     }      return array; }