LeetCode题解(0128)：最长连续序列(Python)

题目：​​原题链接​​（困难）

标签：数组、哈希表、并查集

解法一：

class Solution:
    class IntervalArray:
        class Interval:
            __slots__ = ("l", "r")

            def __init__(self, l, r):
                self.l = l
                self.r = r

            def __len__(self):
                return self.r - self.l + 1

            def __repr__(self):
                return str(str(self.l) + "-" + str(self.r))

        def __init__(self):
            self.mapping = collections.defaultdict(list)

        def add(self, x):
            # 处理当前数值不与任何序列相邻的情况
            if x not in self.mapping or len(self.mapping[x]) == 0:
                interval = self.Interval(x, x)
                self.mapping[x - 1].append(interval)
                self.mapping[x + 1].append(interval)

            # 处理当前数值只与一个序列相邻的情况
            elif len(self.mapping[x]) == 1:
                interval = self.mapping[x][0]
                del self.mapping[x]
                if x == interval.l - 1:
                    interval.l -= 1
                    self.mapping[x - 1].append(interval)
                else:
                    interval.r += 1
                    self.mapping[x + 1].append(interval)

            # 处理当前数值与两个序列相邻的情况
            else:
                interval1, interval2 = self.mapping[x][0], self.mapping[x][1]
                del self.mapping[x]
                if interval1.l > interval2.l:
                    interval1, interval2 = interval2, interval1
                interval = self.Interval(interval1.l, interval2.r)
                self.mapping[interval1.l - 1].remove(interval1)
                self.mapping[interval2.r + 1].remove(interval2)
                self.mapping[interval1.l - 1].append(interval)
                self.mapping[interval2.r + 1].append(interval)

    def longestConsecutive(self, nums: List[int]) -> int:
        array = self.IntervalArray()
        for num in set(nums):
            array.add(num)

        ans = 0
        for intervals in array.mapping.values():
            for interval in intervals:
                ans = max(ans,len(interval))
        return ans