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import java.util.List;
import java.util.Comparator;
import static java.util.Collections.swap;
public class Heap<T>
{
private List<T> list;
private Comparator<T> cmp;
private int size;
public int getSize()
{
return size;
}
public int getLength()
{
return list.size();
}
public T get(int i)
{
return list.get(i);
}
public void heapify(int i)
{
int right = i + 1 << 1;
int left = right - 1;
int largest = i;
if (left < size && cmp.compare(get(left), get(largest)) > 0)
largest = left;
if (right < size && cmp.compare(get(right), get(largest)) > 0)
largest = right;
if (largest != i)
{
swap(list, i, largest);
heapify(largest);
}
}
public Heap(List<T> a, Comparator<T> c)
{
list = a;
size = a.size();
cmp = c;
for (int i = size >> 1; i-- > 0;)
heapify(i);
}
public T pop() throws RuntimeException
{
if (size < 1)
throw new RuntimeException("heap underflow");
swap(list, 0, --size);
heapify(0);
return get(size);
}
}
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