力扣 hot100 最长连续序列 哈希去重 双指针

128. 最长连续序列

⭐ AC code

class Solution {
    public int longestConsecutive(int[] nums) 
    {
		if (nums.length == 0)// 特判为空的数组，返回0
			return 0;
//		set实现去重
		HashSet<Integer> set = new HashSet<>();
		for (int x : nums)
			set.add(x);
		Object[] array = set.toArray();
//		数组复制
		Integer[] numbers = Arrays.copyOfRange(array, 0, array.length, Integer[].class);
		Arrays.sort(numbers);
		int l = 0;
		int r = 1;
		int ans = 1;
//		双指针
		while (r <= numbers.length)
		{
			if (r == numbers.length)
			{
				ans = Math.max(ans, r - l);
				break;
			}
			if (numbers[r - 1] + 1 == numbers[r])
				r++;
			else
			{
				ans = Math.max(ans, r - l);
				l = r++;
			}
		}
		return ans;
	}
}
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