STL 堆操作

转自：http://blog.sina.com.cn/s/blog_622118670100f0ma.html

STL里面的堆操作一般用到的只有4个:make_heap();、pop_heap();、push_heap();、sort_heap();

他们的头文件函数是#include <algorithm>

首先是make_heap();

他的函数原型是：void make_heap(first_pointer,end_pointer,compare_function);

一个参数是数组或向量的头指针，第二个向量是尾指针。第三个参数是比较函数的名字。在缺省的时候，默认是大跟堆。（下面的参数都一样就不解释了）

作用：把这一段的数组或向量做成一个堆的结构。范围是(first,last)

然后是pop_heap();

它的函数原型是：void pop_heap(first_pointer,end_pointer,compare_function);

作用：pop_heap()不是真的把最大（最小）的元素从堆中弹出来。而是重新排序堆。它
把first和last交换，然后将[first,last-1)的数据再做成一个堆。

接着是push_heap() void pushheap(first_pointer,end_pointer,compare_function);

作用：push_heap()假设由[first,last-1)是一个有效的堆，然后，再把堆中的新元素加
进来，做成一个堆。

最后是sort_heap()void sort_heap(first_pointer,end_pointer,compare_function);

作用是sort_heap对[first,last)中的序列进行排序。它假设这个序列是有效堆。（当然
，经过排序之后就不是一个有效堆了）

下面是例程：

#include<algorithm>

#include<cstdio>

using namespace std;

bool cmp(int a,int b)

{
    return a>b;
}
int main()
{
    int i,number[20]={29,23,20,22,17,15,26,51,19,12,35,40};

    make_heap(&number[0],&number[12]);

    //结果是:51 35 40 23 29 20 26 22 19 12 17 15

    for(i=0;i<12;i++)

        printf("%d ",number[i]);

    printf("\n");

    make_heap(&number[0],&number[12],cmp);

    //结果：12 17 15 19 23 20 26 51 22 29 35 40

    for(i=0;i<12;i++)

        printf("%d ",number[i]);

    printf("\n");

    //加入元素8

    number[12]=8;

    //加入后调整

    push_heap(&number[0],&number[13],cmp);

    //结果：8 17 12 19 23 15 26 51 22 35 40 20

    for(i=0;i<13;i++)

        printf("%d ",number[i]);

    printf("\n");

    //弹出元素8

    pop_heap(&number[0],&number[13],cmp);

    //结果：12 17 15 19 23 20 26 51 22 29 35 40

    for(i=0;i<13;i++)

        printf("%d ",number[i]);

    printf("\n");

    sort_heap(&number[0],&number[12],cmp);

    //结果不用说都知道是有序的了！

    for(i=0;i<12;i++)

        printf("%d ",number[i]);

    return 0;

}
Compile options needed: /GX
//
// heap_functions.cpp : Illustrates how to use the
//                      make_heap, sort_heap, push_heap
//                      and pop_heap functions.
//
// Functions:
//
//    make_heap : convert a sequence to a heap
//    sort_heap : sort a heap
//    push_heap : insert an element in a heap
//    pop_heap  : remove the top element from a heap
//
// Written by Kalindi Sanghrajka
// of Microsoft Product Support Services,
// Software Core Developer Support.
// Copyright (c) 1996 Microsoft Corporation. All rights reserved.
//////////////////////////////////////////////////////////////////////

// disable warning C4786: symbol greater than 255 character,
// okay to ignore
#pragma warning(disable: 4786)

#include <iostream>
#include <algorithm>
#include <functional>
#include <vector>
using namespace std;
void main()
{
    const int VECTOR_SIZE = 8 ;

    // Define a template class vector of int
    typedef vector<int, allocator<int> > IntVector ;

    //Define an iterator for template class vector of strings
    typedef IntVector::iterator IntVectorIt ;

    IntVector Numbers(VECTOR_SIZE) ;

    IntVectorIt it ;

    // Initialize vector Numbers
    Numbers[0] = 4 ;
    Numbers[1] = 10;
    Numbers[2] = 70 ;
    Numbers[3] = 10 ;
    Numbers[4] = 30 ;
    Numbers[5] = 69 ;
    Numbers[6] = 96 ;
    Numbers[7] = 100;

    // print content of Numbers
    cout << "Numbers { " ;
    for(it = Numbers.begin(); it != Numbers.end(); it++)
        cout << *it << " " ;
    cout << " }\n" << endl ;

    // convert Numbers into a heap
    make_heap(Numbers.begin(), Numbers.end()) ;

    cout << "After calling make_heap\n" << endl ;

    // print content of Numbers
    cout << "Numbers { " ;
    for(it = Numbers.begin(); it != Numbers.end(); it++)
        cout << *it << " " ;
    cout << " }\n" << endl ;

    // sort the heapified sequence Numbers
    sort_heap(Numbers.begin(), Numbers.end()) ;

    cout << "After calling sort_heap\n" << endl ;

    // print content of Numbers
    cout << "Numbers { " ;
    for(it = Numbers.begin(); it != Numbers.end(); it++)
        cout << *it << " " ;
    cout << " }\n" << endl ;

    //insert an element in the heap
    Numbers.push_back(7) ;
    push_heap(Numbers.begin(), Numbers.end()) ;

    // you need to call make_heap to re-assert the
    // heap property
    make_heap(Numbers.begin(), Numbers.end()) ;

    cout << "After calling push_heap and make_heap\n" << endl ;

    // print content of Numbers
    cout << "Numbers { " ;
    for(it = Numbers.begin(); it != Numbers.end(); it++)
        cout << *it << " " ;
    cout << " }\n" << endl ;

    // remove the root element from the heap Numbers
    pop_heap(Numbers.begin(), Numbers.end()) ;

    cout << "After calling pop_heap\n" << endl ;

    // print content of Numbers
    cout << "Numbers { " ;
    for(it = Numbers.begin(); it != Numbers.end(); it++)
        cout << *it << " " ;
    cout << " }\n" << endl ;
}
程序输出为：

Numbers { 4 10 70 10 30 69 96 100 }

之后调用 make_heap

Numbers { 100 30 96 10 4 69 70 10 }

之后调用 sort_heap

Numbers { 4 10 10 30 69 70 96 100 }

之后调用 push_heap 和 make_heap

Numbers { 100 69 96 30 4 70 10 10 7 }

之后调用 pop_heap

Numbers { 96 69 70 30 4 7 10 10 100 }