堆排序-c++

 1 /*************************************************************************
 2     > File Name: HeapSort.cpp
 3     > Author: zhoukang
 4     > Mail: zhoukang199191@126.com 
 5     > Created Time: 2014年08月11日 星期一 22时36分38秒
 6  ************************************************************************/
 7 
 8 #include <iostream>
 9 #include <vector>
10 #include <algorithm>
11 using namespace std;
12 
13 void max_heapfy(vector<int> & A,int index,int heapsize)
14 {
15     int l = 2*index+1;
16     int r = 2*index+2;
17 
18     int largest = index;
19     if(l <= heapsize && A[l] > A[index])
20         largest = l;
21     if(r <= heapsize && A[r] > A[largest])
22         largest = r;
23     if(largest != index)
24     {
25         swap(A[index],A[largest]);
26         max_heapfy(A,largest,heapsize);
27     }
28 }
29 
30 void build_max_heap(vector<int> &A,int heapsize)
31 {
32 //    assert(heapsize >= 0);
33     int i;
34     for(i = heapsize/2-1 ; i >= 0 ; --i)
35         max_heapfy(A,i,heapsize);
36 }
37 
38 void heap_sort(vector<int> &A,int heapsize)
39 {
40     build_max_heap(A,heapsize);
41     int i;
42     for(i = heapsize-1; i > 0 ; --i )
43     {
44         swap(A[0],A[i]);
45         max_heapfy(A,0,i);
46     }
47 }
48 
49 int main()
50 {
51     cout<<"before"<<endl;
52     vector<int> A;
53     A.push_back(3);
54     A.push_back(1);
55     A.push_back(2);
56     heap_sort(A,3);
57 }