力扣128. 最长连续序列

 

自己没想到最优解，题解的思路记录一下吧

题目：【https://leetcode.cn/problems/longest-consecutive-sequence/description/?envType=study-plan-v2&envId=top-interview-150】

 

class Solution {
public:
    int longestConsecutive(vector<int>& nums) {
        unordered_set<int> cache;
        int ret = 0;

        for (auto n : nums)
            cache.insert(n);

        for (auto n : cache) {
            if (0 == cache.count(n - 1)) {
                int tret = 1;
                while (cache.count(++n)) tret++;
                ret = tret > ret ? tret : ret;
            }
        }
        return ret;
    }
};