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  1. import java.util.ArrayList;
  2. import java.util.Arrays;
  3. import java.util.Collection;
  4. import java.util.Iterator;
  5. import java.util.List;
  6. import java.util.NoSuchElementException;
  7. import java.util.PriorityQueue;
  8.  
  9. class SuperIterator<T extends Comparable<T>> implements Iterator<T> {
  10.  
  11.     private List<Iterator<T>> iters;
  12.     private PriorityQueue<T> queue = new PriorityQueue<>();
  13.  
  14.     public static void main (String[] args) throws java.lang.Exception {
  15.     	// Test
  16.         Iterator<Integer> iter1 = Arrays.asList(1, 5).iterator();
  17.         Iterator<Integer> iter2 = Arrays.asList(2, 4).iterator();
  18.         Iterator<Integer> iter3 = Arrays.asList(1, 2, 4, 5).iterator();
  19.  
  20.         SuperIterator<Integer> superIter = new SuperIterator<>(iter1, iter2, iter3);
  21.         while (superIter.hasNext()) {
  22.             System.out.println(superIter.next());
  23.         }
  24.     }
  25.  
  26.     public SuperIterator(Collection<Iterator<T>> iters) {
  27.       this.iters = new ArrayList<>(iters);
  28.     }
  29.  
  30.     public SuperIterator(Iterator<T>... iters) {
  31.       this.iters = new ArrayList<>(Arrays.asList(iters));
  32.     }
  33.  
  34.     @Override
  35.     public boolean hasNext() {
  36.         return !(iters.isEmpty() && queue.isEmpty());     
  37.     }
  38.  
  39.     @Override
  40.     public T next() {
  41.         iters.removeIf(i -> !i.hasNext());
  42.         iters.forEach(i -> queue.add(i.next()));
  43.         if (queue.isEmpty()) {
  44.             throw new NoSuchElementException();
  45.         }
  46.         return queue.poll();
  47.     }  
  48. }
Success #stdin #stdout 0.14s 2184192KB
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https://ideone.com/CjsgV2
language:
Java (HotSpot 12)
created:
4 years ago
visibility:
public

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