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)

#include <stdio.h>
 
#define N 2000000
#define INF -1000000
 
int size, stuck[N];
 
void increaseKey(int i, int key) {
    int tmp;
    if (key < stuck[i]) return;
    stuck[i] = key;
    while(i>1 && stuck[i/2]<stuck[i]) {
        tmp = stuck[i];
        stuck[i] = stuck[i/2];
        stuck[i/2] = tmp;
        i=i/2;
    }
}
 
void maxHeapify(int i) {
    int l,r,max;
    int tmp;
 
    l = i*2;
    r = i*2+1;
 
    if (l <= size && stuck[l] > stuck[i]) max = l;
    else max = i;
    if (r <= size && stuck[r] > stuck[max]) max = r;
 
    if (max != i) {
        tmp = stuck[i];
        stuck[i] = stuck[max];
        stuck[max] = tmp;
        maxHeapify(max);
    }
}
 
void insert(int key) {
    size++;
    stuck[size] = INF;
    increaseKey(size, key);
}
 
int extract() {
    int max;
    if (size < 1) return INF;
    max = stuck[1];
    stuck[1] = stuck[size--];
    maxHeapify(1);
    return max;
}
 
int main() {
    int k;
    char com[10];
 
    while (1) {
        scanf("%s", com);
        if (com[0] == 'e' && com[1] == 'n') break;
        if (com[0] == 'i') {
            scanf("%d", &k);
            insert(k);
        } else {
            printf("%d\n", extract());
        }
    }
 
    return 0;
}