Leetcode 31. Next Permutation

class Solution {
public:
    void nextPermutation(vector<int>& nums) {
        int index = -1;
        int min = 0;
        for(int i = nums.size() - 1; i > 0; i--) {
            if(nums[i] > nums[i - 1] ) {
                index = i - 1;
                min = i;
                break;
            }
        }
        if(index == -1) {
            return reverse(nums.begin(), nums.end());
        }
        for(int i = index + 1; i < nums.size(); i++) {
            if(nums[i] > nums[index] && nums[i] < nums[min]) {
                min = i;
            }
        }
        swap(nums[index], nums[min]);
        sort(nums.begin() + index + 1, nums.end());
    }

private:
    void swap(int& a, int& b) {
        int temp = a;
        a = b;
        b = temp;
    }
};