leetcode 之Longest Consecutive Sequence（六）

int longestConsecutive(const vector<int> &num)
      {
          unordered_map<int, bool> used;
          for (auto i : num)used[i] = false;
          int longest = 0;
          for (auto i : num)
          {
              if (used[i])continue;

              int length = 1;
              used[i] = true;
              for (int j = i + 1; used.find(j) != used.end(); j++)
              {
                  used[j] = true;
                  length++;
              }
              for (int j = i - 1; used.find(j) != used.end(); j--)
              {
                  used[j] = true;
                  length++;
              }

              longest = max(longest, length);

              
          }

          return longest;
      }