LeetCode – Refresh – Longest Consecutive Sequence

It use the hashset to do the tricks.

class Solution {
public:
    int longestConsecutive(vector<int> &num) {
        int len = num.size(), result = 0;
        if (len < 2) return len;
        unordered_set<int> sets;
        for (int i = 0; i < len; i++) {
            sets.insert(num[i]);
        }
        while (!sets.empty()) {
            int start = *sets.begin(), end = start;
            while (sets.erase(start-1)) start--;
            while (sets.erase(end)) end++;
            result = max(result, end-start);
        }
        return result;
    }
};