leetcode(128)最长连续序列

最长连续序列

解题思路：哈希表

class Solution {
    public int longestConsecutive(int[] nums) {
        HashSet<Integer> 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;
    }
}