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  1. Prepare
  2. Java
  3. Data Structures
  4. Java Dequeue
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Java Dequeue

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338 Discussions

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  • BrendaLando45
     + 0 comments

    This is a really clear introduction to deques and their usage. I like how it shows both LinkedList and ArrayDeque implementations — it helps beginners see the options available in Java. funinexchange247

  • sumit_next21
     + 0 comments

    simplest logic

    Scanner in = new Scanner(System.in);
            Deque<Integer> deque = new ArrayDeque<>();
            
            int n = in.nextInt();
            int m = in.nextInt();
            int max = 0;
            for (int i = 0; i < n; i++) {
                int num = in.nextInt();
                deque.add(num);
                if(deque.size()==m){
                    int size = new HashSet<Integer>(deque).size();
                    if(max<size) max = size;
                    deque.removeFirst();
                }
            }
            in.close();
            System.out.println(max);

  • tusharvyavahare1
     + 0 comments
    public class Solution {

    public static void main(String[] args) {
      Scanner sc=new Scanner(System.in);
      int n=sc.nextInt();
      int m=sc.nextInt();
      Deque<Integer> deq=new ArrayDeque<>();
      Map<Integer,Integer> hm=new HashMap<>();
      int res=0;
      for(int i=0;i<n;i++){
        int ele=sc.nextInt();
        deq.offerLast(ele);
        hm.put(ele,hs.getOrDefault(ele, 0)+1);
        if(deq.size()==m){
            res=Math.max(res, hm.size());
            int out=deq.pollFirst();
            int count=hm.get(out);
            if(count==1){
                hm.remove(out);
            }else{
                hm.put(out,hs.get(out)-1);
            }
            
        }
      }
      System.out.println(res);
    }
}

  • bdeesorn
     + 0 comments

    Set took too much time.

    public class Solution {

    public static void main(String[] args) {
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
        try (BufferedReader bIn = new BufferedReader(new InputStreamReader(System.in))) {
            // get max length;
            String line = bIn.readLine();
            int setLength = Integer.valueOf(line.split(" ")[1]).intValue();
            
            // find max unique number
            line = bIn.readLine();
            Deque<Long> l = new LinkedList<>();
            Map<Long, Integer> m = new HashMap<>();
            int maxUnique = 0;
            
            for (String str : line.split(" ")) {
                Long val = Long.valueOf(str);
                l.add(val);
                
                if (m.containsKey(val)) {
                    m.put(val, m.get(val) + 1);
                } else {
                    m.put(val, 1);
                }
                
                if (l.size() == setLength) {
                    maxUnique = Math.max(maxUnique, m.size());
                    Long clearVal = l.poll();
                    int sum = m.get(clearVal) - 1;
                    if (sum == 0) {
                        m.remove(clearVal);
                    } else {
                        m.put(clearVal, sum);
                    }
                }
            }
            
            System.out.println(maxUnique);
        } catch (Exception e) {
            //
        }
    }
}

  • shaunw3bb17
     + 0 comments

    my solution: import java.util.*; public class test { public static void main(String[] args) { Scanner in = new Scanner(System.in); Deque deque = new ArrayDeque<>(); Set set = new HashSet<>(); int n = in.nextInt(); int m = in.nextInt(); int max = 0;

            for (int i = 0; i < n; i++) {
            int num = in.nextInt();
            deque.addLast(num);
            set.add(num);

        if(deque.size() == m){
            max = Math.max(max, set.size());
            int first = deque.removeFirst();
            if(!deque.contains(first)){
                set.remove(first);
            }
        }
    }
   System.out.println(max); 
 }

}