最长连续序列

解题思路：哈希表

class Solution {    public int longestConsecutive(int[] nums) {        HashSet
     
       set = new HashSet<>();        for(int i:nums) {            set.add(i);        }        int currentNum = 0;        int len = 0;        int lenMax = 0;        for(int i:nums) {            if(!set.contains(i-1)) {                currentNum = i;                len = 1;                while(set.contains(++currentNum)) {                    ++len;                }                lenMax = Math.max(len, lenMax);            }        }        return lenMax;    }}