import java.util.*;
public class Solution {

    //方法一:时间复杂度为O(nlog(n))
    public int longestConsecutive(int[] num) {
        if(num==null||num.length==0)
          return 0;
        Arrays.sort(num);
        ArrayList<Integer>list=new ArrayList<>();
        int count=1;
        for(int i=1;i!=num.length;i++){
          if(num[i]-num[i-1]==1){
                count++;
          }else if(num[i]-num[i-1]==0)
          {
               continue;
          }else{
              list.add(count);
              count=1;
          }  
        }

        for(int k:list){
            count=Math.max(count,k);
        }
        return count;
    }

    //方法二:时间复杂度为O(n)
    public int longestConsecutive2(int[] num){

         if(num==null||num.length==0){
             return 0;
         }
         HashSet<Integer>set=new HashSet<>();
         for(int k:num){
            set.add(k);
         }
         int max=1;
         for(int k:num){
              if(set.remove(k)){
                  int val=k;
                  int count=1;
                  int val_small=val-1;
                  int val_big=val+1;
                  while(set.remove(val_small)) {
                      count++;
                      val_small--;
                  }
                  while(set.remove(val_big)){
                      count++;
                      val_big++;
                  }
                  max=Math.max(max,count);
              }

         }
         return max;
    }

    public static void main(String[]args){
        //System.out.println("Hello");
        Solution s=new Solution();
        int[]num={1,2,0,1};
        System.out.println(s.longestConsecutive(num));
        System.out.println(s.longestConsecutive2(num));
    }
}