1 /**
2 * 大根堆。从STL中获得。
3 */
4
5 #include <iostream>
6 #include <ctime>
7 #include <cmath>
8 #include <cstdlib>
9
10 using namespace std;
11
12 void _push_heap(int *start, int holeIndex, int topIndex, int value)
13 {
14 int parent = (holeIndex - 1) / 2;
15 while (holeIndex > topIndex && *(start + parent) < value)
16 {
17 *(start + holeIndex) = *(start + parent);
18 holeIndex = parent;
19 parent = (holeIndex - 1) / 2;
20 }
21 *(start + holeIndex) = value;
22 }
23
24 void adjust_heap(int *start, int holeIndex, int length, int value)
25 {
26 int topIndex = holeIndex;
27 int secondChild = 2 * holeIndex + 2;
28
29 while (secondChild < length)
30 {
31 // 大根堆的调整
32 if (*(start + secondChild) < *(start + secondChild - 1))
33 secondChild--;
34 *(start + holeIndex) = *(start + secondChild);
35 holeIndex = secondChild;
36 secondChild = 2 * holeIndex + 2;
37 }
38
39 if (secondChild == length) {
40 *(start + holeIndex) = *(start + secondChild - 1);
41 holeIndex = secondChild - 1;
42 }
43
44 _push_heap(start, holeIndex, topIndex, value);
45 }
46
47
48 void push_heap(int *start, int *end)
49 {
50 _push_heap(start, start - end - 1, 0, *(end - 1));
51 }
52
53 int pop_heap(int *start, int *end)
54 {
55 int result = *start;
56 adjust_heap(start, 0, end - start, *(end - 1));
57
58 return result;
59 }
60
61 void make_heap(int *start, int *end)
62 {
63 if (end - start < 2) return ;
64 int length = end - start;
65 int parent = (length - 2) / 2;
66
67 while (true) {
68 adjust_heap(start, parent, length, *(start + parent));
69 if (parent == 0) return;
70 parent--;
71 }
72 }
73
74 void sort_heap(int *start, int *end)
75 {
76 while (end - start > 1)
77 cout << pop_heap(start, end--) << "\t" ;
78 }
79
80 int test(void)
81 {
82 enum {maxsize = 500};
83 int a[maxsize], i;
84 srand((int)time(0));
85
86 cout << "test array: " << endl;
87 for (i = 0; i < maxsize; i++)
88 {
89 a[i] = rand();
90 cout << a[i] << "\t";
91 }
92 int size = sizeof(a) / sizeof(int);
93 cout << endl << endl;
94 cout << "result: " << endl;
95
96 make_heap(a, a + size);
97 sort_heap(a, a + size);
98
99 return 0;
100 }
101
102 int main()
103 {
104 test();
105
106 return 0;
107 }
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