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 JAVA (judge verdict: Accepted)


import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.HashMap;
import java.util.Map;
import java.util.PriorityQueue;

public class Main {
	public static void main(String[] args) throws IOException {
		PriorityQueue<Integer> queue = new PriorityQueue<Integer>();
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringBuffer sb = new StringBuffer();
		Map<Integer, Integer> map = new HashMap<Integer, Integer>();

		end: {
			while (true) {
				String str = br.readLine();
				switch (str.substring(0, 2)) {

				case "in":
					// insert????????????
					int insert = Integer.parseInt((String) str.subSequence(7, str.length()));
					int key = 2000000000 - insert;
					map.put(key, insert);
					queue.add(key);
					
					break;

				case "ex":
					// extract????????????
					key = queue.poll();
					sb.append(map.get(key) + "\n");
					break;

				case "en":
					// end??\??????????????????
					break end;
				}
			}
		}
		System.out.print(sb.toString());
	}
}