leetcode 23：longest-consecutive-sequence

 1  int longestConsecutive(vector<int>& num) {
 2        if(num.size() == 0)
 3            return 0;
 4         set<int> st(num.begin(),num.end());
 5         int count = 1;
 6         for(int i = 0;i < num.size();i++)
 7         {
 8             int temp = num[i];
 9             if(st.count(temp) == 0)
10                 continue;
11             int l = temp - 1;
12             int r = temp + 1;
13             while(st.count(l) != 0)
14             {
15                 st.erase(l);
16                 l--;
17             }
18             while(st.count(r) != 0)
19             {
20                 st.erase(r);
21                 r++;
22             }
23             count = max(count,r-l-1);
24         }
25         return count;
26     }