stl中的heap使用

stl中的堆默认是最大堆，要想用最小堆的话，必须要在push_heap,pop_heap,make_heap等每一个函数后面加第三个参数greater<int>()，括号不能省略。

1、make_heap：使序列变成堆

原型：
template <class RandomAccessIterator>
  void make_heap ( RandomAccessIterator first, RandomAccessIterator last );

template <class RandomAccessIterator, class Compare>
  void make_heap ( RandomAccessIterator first, RandomAccessIterator last,
                   Compare comp );

范例：

// range heap example#include <iostream>#include <algorithm>#include <vector>using namespace std;int main () {  int myints[] = {10,20,30,5,15};  vector<int> v(myints,myints+5);  make_heap (v.begin(),v.end());  cout << "initial max heap   : " << v.front() << endl;  pop_heap (v.begin(),v.end()); v.pop_back();  cout << "max heap after pop : " << v.front() << endl;  v.push_back(99); push_heap (v.begin(),v.end());  cout << "max heap after push: " << v.front() << endl;  sort_heap (v.begin(),v.end());  cout << "final sorted range :";  for (unsigned i=0; i<v.size(); i++) cout << " " << v[i];  cout << endl;  return 0;}

2、push_heap：压栈(入栈)
原型：
template <class RandomAccessIterator>
  void push_heap ( RandomAccessIterator first, RandomAccessIterator last );

template <class RandomAccessIterator, class Compare>
  void push_heap ( RandomAccessIterator first, RandomAccessIterator last,
                   Compare comp );

3、pop_heap：弹栈(出栈)

原型：
template <class RandomAccessIterator>
  void pop_heap ( RandomAccessIterator first, RandomAccessIterator last );

template <class RandomAccessIterator, class Compare>
  void pop_heap ( RandomAccessIterator first, RandomAccessIterator last,
                   Compare comp );

范例:

// range heap example#include <iostream>#include <algorithm>#include <vector>using namespace std;int main () {  int myints[] = {10,20,30,5,15};  vector<int> v(myints,myints+5);  vector<int>::iterator it;  make_heap (v.begin(),v.end());  cout << "initial max heap   : " << v.front() << endl;  pop_heap (v.begin(),v.end()); v.pop_back();  cout << "max heap after pop : " << v.front() << endl;  v.push_back(99); push_heap (v.begin(),v.end());  cout << "max heap after push: " << v.front() << endl;  sort_heap (v.begin(),v.end());  cout << "final sorted range :";  for (unsigned i=0; i<v.size(); i++) cout << " " << v[i];  cout << endl;  return 0;}

4、sort_heap：对堆排序

原型：template <class RandomAccessIterator>
  void sort_heap ( RandomAccessIterator first, RandomAccessIterator last );

template <class RandomAccessIterator, class Compare>
  void sort_heap ( RandomAccessIterator first, RandomAccessIterator last,
                   Compare comp );

范例：

// range heap example#include <iostream>#include <algorithm>#include <vector>using namespace std;int main () {  int myints[] = {10,20,30,5,15};  vector<int> v(myints,myints+5);  vector<int>::iterator it;  make_heap (v.begin(),v.end());  cout << "initial max heap   : " << v.front() << endl;  pop_heap (v.begin(),v.end()); v.pop_back();  cout << "max heap after pop : " << v.front() << endl;  v.push_back(99); push_heap (v.begin(),v.end());  cout << "max heap after push: " << v.front() << endl;  sort_heap (v.begin(),v.end());  cout << "final sorted range :";  for (unsigned i=0; i<v.size(); i++) cout << " " << v[i];  cout << endl;  return 0;}

注：例子来源于www.cplusplus.com网站