class Solution {public:    int longestConsecutive(vector<int> &num) {        int len = num.size();                int max_cons = 0;        int cur_cons = 0;                unordered_map<int, int> sgn;        unordered_map<int, int>::iterator iter;        for (int i=0; i<len; i++) {            sgn.insert(make_pair(num[i], 0x1));        }                for (int i=0; i<len; i++) {            iter = sgn.find(num[i]);            if (iter == sgn.end()) continue; // illegal case, should not hit            if (iter->second == 0) continue; // this range has been scaned            iter->second = 0;            cur_cons = 1;                        int try_n = num[i];            // search towards negative            while (try_n != INT_MIN) {                try_n--;                iter = sgn.find(try_n);                if (iter == sgn.end()) break;                iter->second = 0;                cur_cons++;            }            try_n = num[i];            // search towards positive            while (try_n != INT_MAX) {                try_n++;                iter = sgn.find(try_n);                if (iter == sgn.end()) break;                iter->second = 0;                cur_cons++;            }            if (cur_cons > max_cons) max_cons = cur_cons;        }                return max_cons;    }};