Longest Consecutive Sequence c++

Given an unsorted array of integers, find the length of the longest consecutive elements sequence.

For example,
Given [100, 4, 200, 1, 3, 2],
The longest consecutive elements sequence is [1, 2, 3, 4]. Return its length: 4.

class Solution {

public:

    int longestConsecutive(vector<int>& nums) {

        int max = 0;

        int cnt = 0;

        if (nums.size() == 0 ) return 0;

        sort(nums.begin(), nums.end());

        for (int i = 0; i< nums.size(); i++) {

            if (nums[i]+1 == nums[i+1]) {

                cnt++;

            } else if (nums[i+1] > nums[i]){

                if (cnt>max) max = cnt;

                cnt = 0;

            }

        }

        if (cnt>max) max = cnt;

        return max+1;

    }

};