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>
#include<stdlib.h>
#include<string.h>
#define mymalloc(p,n) {p = malloc((n)*sizeof(*p));if ((p)==NULL) {printf("not enough memory?\n"); exit(1);};}

typedef struct{
	long *A;
	long n;
}heap;

int p(int i){return (i/2);}
int l(int i){return (2*i);}
int r(int i){return (2*i+1);}

void swap (long *i,long *j){
	long tmp;
	tmp=*i;
	*i=*j;
	*j=tmp;
}

void maxHeapify(heap *H,long i){
	long *A;
	long n,largest,temp;
	A=H->A;n=H->n;
	if(l(i)<=n && A[l(i)] > A[i]){
		largest = l(i);
	}else{
		largest = i;
	}
	if(r(i)<=n && A[r(i)] > A[largest]){
		largest = r(i);
	}
	if(largest!=i){
		swap(&A[i],&A[largest]);
		maxHeapify(H,largest);
	}
}

void insert(heap *H,long key){
	long n,i;
	long *A;
	n=H->n;A=H->A;
	A[n+1]=key;
	i=n+1;
	while(p(i)>=1 && A[p(i)]<A[i]){
		swap(&A[p(i)],&A[i]);
		i=p(i);
	}
	H->n++;
}

long extMax(heap *H){
	long max,n;
	long *A;
	n=H->n;A=H->A;
	max=A[1];
	A[1]=A[n];
	maxHeapify(H,1);
	H->n--;
	return max;
}
	
main(){
	long n,i,m;
	heap *H;
	char s[10];
	mymalloc(H,1);
	H->n=0;
	mymalloc(H->A,2000000);
	while(1){
		scanf(" %s",s);
		if(strcmp(s,"insert")==0){
			scanf(" %ld",&m);
			insert(H,m);
		}else{
		if(strcmp(s,"extract")==0){
			m=extMax(H);
			printf("%ld\n",m);
		}else{
		if(strcmp(s,"end")==0){
			break;
		}}}
	}
	return 0;
}