leetcode hot 07

合集 - leetcode hot100(25)

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收起

解题思路：因为可能存在相同的数，所以运用到HashSet去重，然后遍历hashset每个数num，如果num-1不在hashset中，那么num就是序列开头，然后继续查找num++，直到hashset中找不到为止，记录长度，最后取最长的长度。

class Solution {
    public int longestConsecutive(int[] nums) {
        Set<Integer> hashset = new HashSet<>();
        int maxlength = 0;
        for(int num:nums) hashset.add(num);
        for(int num:hashset){
            if(!hashset.contains(num-1)){
                int i = 0;
                while(hashset.contains(num+i)){
                    i++;
                }
                // if(i>maxlength) maxlength=i;
                maxlength = Math.max(i,maxlength);
            }
        }
        return maxlength;
    }
}