[leetcode] Longest Consecutive Sequence

Longest Consecutive Sequence

class Solution {public:    int longestConsecutive(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]){//i已经标记过                continue;            }            int length=1;            used[i]=true;//标记i                        for(int j=i+1;used.find(j)!=used.end();++j){//找比i大的                used[j]=true;                length++;            }                        for(int j=i-1;used.find(j)!=used.end();--j){//找比i小的                used[j]=true;                length++;            }                        longest=max(longest,length);        }        return longest;    }};