STL中的堆操作
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 }
作 者:fengbohello
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