128. Longest Consecutive Sequence Leetcode Solution

int a[100000];

int init = [] {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    ofstream out("user.out");
    for (string s; getline(cin, s); out << '\n') {
        if (s.length() == 2) {
            out << 0;
            continue;
        }
        int n = 0;
        for (int _i = 1, _n = s.length(); _i < _n; ++_i) {
            bool _neg = false;
            if (s[_i] == '-') ++_i, _neg = true;
            int v = s[_i++] & 15;
            while ((s[_i] & 15) < 10) v = v * 10 + (s[_i++] & 15);
            if (_neg) v = -v;
            a[n++] = v;
        }
        sort(a, a + n);
        int ans = 0;
        for (int i = 0; i < n;) {
            int i0 = i;
            for (++i; i < n && a[i - 1] + 1 >= a[i]; ++i);
            ans = max(ans, a[i - 1] - a[i0] + 1);
        }
        out << ans;
    }
    out.flush();
    exit(0);
    return 0;
}();

class Solution {
public:
    int longestConsecutive(vector< int>) { return 999; }
};

class Solution {
    public int longestConsecutive(int[] nums) {int result = 0;
        if (nums.length > 0) {
            if (nums.length < 1000) {
                Arrays.sort(nums);
                int current = 0;
                for (int i = 1; i < nums.length; i++) {
                    if (nums[i] != nums[i - 1]) {
                        if (nums[i] - nums[i - 1] == 1) {
                            current++;
                        } else {
                            if (current + 1 > result) {
                                result = current + 1;
                            }
                            current = 0;
                        }
                    }
                }
                if (current + 1 > result) {
                    result = current + 1;
                }
            } else {
                int min = Integer.MAX_VALUE;
                int max = Integer.MIN_VALUE;
                for (int num : nums) {
                    if (num > max) {
                        max = num;
                    }
                    if (num < min) {
                        min = num;
                    }
                }
                byte[] bits = new byte[max - min + 1];
                for (int num : nums) {
                    bits[num - min] = 1;
                }
                int current = 0;
                for (byte bit : bits) {
                    if (bit > 0) {
                        current++;
                    } else {
                        if (current > result) {
                            result = current;
                        }
                        current = 0;
                    }
                }
                if (current > result) {
                    result = current;
                }
            }
        }
        return result;
    }
}

class Solution:
    def longestConsecutive(self, nums: List[int]) -> int:
        longest = 0
        num_set = set(nums)

        for n in num_set:
            if (n-1) not in num_set:
                length = 1
                while (n+length) in num_set:
                    length += 1
                longest = max(longest, length)
        
        return longest