Leetcode Next permutation

Implement next permutation, which rearranges numbers into the lexicographically next greater permutation of numbers.

If Such arrangement is not a possible, it must rearrange it as the lowest possible order (ie, sorted in ascending order).

The replacement must is in-place, do not allocate extra memory.

Here is some examples. Inputs is in the left-hand column and its corresponding outputs is in the right-hand column.
1,2,3→1,3,2
3,2,1→1,2,3
1,1,5→1,5,1

Test instructions: Find a larger sequence than the sequence, and the last one is back to the smallest.

Thought: The same thing done before: the solution

Class Solution {public:    void Nextpermutation (vector<int> &num) {        if (num.size () < 2) return;        int i = Num.size ()-2;        while (Num[i] >= num[i+1] && i! =-1) i--;        if (I < 0) {            reverse (num.begin (), Num.end ());            return;        }        Int J = num.size ()-1;        while (Num[j] <= num[i]) j--;        Swap (Num[i], num[j]);        Reverse (Num.begin () + i + 1, num.end ());}    };

Leetcode Next permutation