Problem:
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Priority Queue

A priority queue is a data structure which maintains a set $S$ of elements, each of with an associated value (key), and supports the following operations:

$insert(S, k)$: insert an element $k$ into the set $S$

$extractMax(S)$: remove and return the element of $S$ with the largest key

Write a program which performs the $insert(S, k)$ and $extractMax(S)$ operations to a priority queue $S$.
The priority queue manages a set of integers, which are also keys for the priority.

Input

Multiple operations to the priority queue $S$ are given. Each operation is given by "insert $k$", "extract" or "end" in a line. Here, $k$ represents an integer element to be inserted to the priority queue.

The input ends with "end" operation.

Output

For each "extract" operation, print the element extracted from the priority queue $S$ in a line.

Constraints

The number of operations $\leq 2,000,000$

$0 \leq k \leq 2,000,000,000$

Sample Input 1

insert 8
insert 2
extract
insert 10
extract
insert 11
extract
extract
end

Sample Output 1

8
10
11
2

Solution in C# (judge verdict: Accepted)



using System;
using System.Linq;
using System.Collections.Generic;
using System.Text;
class Program
{



    static void Main(string[] args)
    {
        string[] inp = null;
        var pq = new PriorityQueue<long>();

        while (true)
        {
            inp = Console.ReadLine().Split(' ');
            if (inp[0][2] == 'd') break;

            if (inp[0][0] == 'i')
            {
                pq.Enqueue(long.Parse(inp[1]));
            }
            else
            {
                Console.WriteLine(pq.Dequeue());
            }

        }
    }


}

public class PriorityQueue<T> where T : IComparable
{
    private List<T> data;

    public PriorityQueue()
    {
        this.data = new List<T>();
    }

    public void Enqueue(T item)
    {
        data.Add(item);
        int ci = data.Count - 1;
        while (ci > 0)
        {
            int pi = (ci - 1) / 2;
            if (data[ci].CompareTo(data[pi]) <= 0)
                break;

            T tmp = data[ci];
            data[ci] = data[pi];
            data[pi] = tmp;
            ci = pi;
        }
    }

    public T Dequeue()
    {
        int li = data.Count - 1;
        T front = data[0];
        data[0] = data[li];
        data.RemoveAt(li);

        --li;
        int pi = 0;
        while (true)
        {
            int ci = pi * 2 + 1;
            if (ci > li)
                break;
            int rc = ci + 1;
            if (rc <= li && data[rc].CompareTo(data[ci]) > 0)
                ci = rc;
            if (data[pi].CompareTo(data[ci]) >= 0)
                break;

            T tmp = data[pi];
            data[pi] = data[ci];
            data[ci] = tmp;
            pi = ci;
        }
        return front;
    }

}