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  1. class CircularBuffer<T> {
  2.   private T[] array = (T[]) (new Object[1<<10]);
  3.   private int start = 0, end = 0;
  4.  
  5.   public T get(int i) {
  6.     assert(0 <= i && i < size());
  7.     return array[mod(start + i)];
  8.   }
  9.  
  10.   public void set(int i, T elem) {
  11.     assert(0 <= i && i < size());
  12.     array[mod(start + i)] = elem;
  13.   }
  14.  
  15.   public void append(T elem) {
  16.     if (size() == array.length) resize();
  17.     array[mod(end++)] = elem;
  18.   }
  19.  
  20.   public void prepend(T elem) {
  21.     if (size() == array.length) resize();
  22.     array[mod(--start)] = elem;
  23.   }
  24.  
  25.   public void dropFirst(int count) {
  26.     assert(0 <= count && count <= size());
  27.     start += count;
  28.   }
  29.  
  30.   public void dropLast(int count) {
  31.     assert(0 <= count && count <= size());
  32.     end -= count;
  33.   }
  34.  
  35.   public int size() {
  36.     return mod(mod(end) - mod(start));
  37.   }
  38.  
  39.   public void clear() {
  40.     start = end = 0;
  41.   }
  42.  
  43.   private int mod(int x) {
  44.     return Math.floorMod(x, array.length);
  45.   }
  46.  
  47.   private void resize() {
  48.     T[] array2 = (T[])(new Object[2*array.length]);
  49.     for(int i = 0; i < size(); i++) {
  50.       array2[i] = get(i);
  51.     }
  52.     end = size();
  53.     start = 0;
  54.     array = array2;
  55.   }
  56.  
  57.   public static void main(String[] args) {
  58.   	CircularBuffer<Integer> buffer = new CircularBuffer<Integer>();
  59.   	for (int i = 0; i < 1027; ++i) {
  60.   		buffer.append(0);
  61.   	}
  62.   	System.out.println(buffer.size());
  63.   }
  64. }
Success #stdin #stdout 0.04s 711168KB
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https://ideone.com/BvlyTm
language:
Java (12.0.1)
created:
7 years ago
visibility:
secret

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