longestConsecutive

class Solution {
public:
    int longestConsecutive(vector<int>& nums) {
        unordered_set<int> numsSet;
        for(auto i : nums)
            numsSet.insert(i);

        int longest = 0;
        for(auto i : numsSet) {
            int len = 0;
            if(numsSet.count(i - 1) == 0){
                while(numsSet.count(i + len) != 0)
                    len ++;
                longest = max(longest, len);
            }
        }
        return longest;
    }
};