Leet Code 128. Longest Consecutive Sequence

 https://leetcode.com/problems/longest-consecutive-sequence/description/

Example 1:

Input: nums = [100,4,200,1,3,2]
Output: 4
Explanation: The longest consecutive elements sequence is [1, 2, 3, 4]. Therefore its length is 4.

• sab number ko HashSet me add kr denge, fir har number ki min aur max range nikalenge.

package pep.Day68;

import java.util.HashSet;

public class LeetCode_128_Longest_Consecutive_Sequence {
    public static void main(String[] args) {
        System.out.println(longestConsecutive(new int[]{100, 4, 3, 200, 2, 1, 0}));
    }

    public static int longestConsecutive(int[] nums) {
        HashSet<Integer> hs = new HashSet<>();
        for (int i : nums)
            hs.add(i);

        int range = 0;
        for (int i : nums) {
            int min = i, max = i;

            if (hs.contains(i)) {
                while (hs.contains(min - 1)) {
                    min = min - 1;
                    hs.remove(min);
                }

                while (hs.contains(max + 1)) {
                    max = max + 1;
                    hs.remove(max);
                }

                range = Math.max(range, max - min + 1);
            }
        }

        return range;
    }
}