Leetcode#128 Longest Consecutive Sequence

 1 int longestConsecutive(vector<int> &num) {
 2   set<int> record;
 3   int maxLength = 0;
 4 
 5   for (auto n : num)
 6     record.insert(n);
 7 
 8   while (!record.empty()) {
 9     int len = 1;
10     int n = *(record.begin());
11     record.erase(n);
12     for (int i = n - 1; record.find(i) != record.end(); i--) {
13       len++;
14       record.erase(i);
15     }
16     for (int i = n + 1; record.find(i) != record.end(); i++) {
17       len++;
18       record.erase(i);
19     }
20     maxLength = max(maxLength, len);
21   }
22 
23   return maxLength;