astar-jps/IndexPriorityQueue.c at master · arirahikkala/astar-jps · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
#include "IndexPriorityQueue.h"
#include <stdlib.h>
#include <string.h>
#include <limits.h>

int smallestPowerOfTwoAfter (int x)
{
        if (x < 0)
                return 0;
        x |= x >> 1;
        x |= x >> 2;
        x |= x >> 4;
        x |= x >> 8;
        x |= x >> 16;
        return x+1;
}

int makeSpace (queue *q, size_t size)
{
        unsigned int newAllocated = smallestPowerOfTwoAfter (size * sizeof(item));

        if (newAllocated <= q->allocated)
                return 0;

        q->root = realloc (q->root, newAllocated);
        if (NULL == q->root)
                exit (1); // I'm a bloody Haskell programmer, I don't have any business trying to do anything fancy when realloc fails

        q->allocated = newAllocated;
        return newAllocated;
}

int placeAtEnd (queue *q, item item)
{
	makeSpace (q, q->size + 1);
	q->root[q->size] = item;
	return q->size++;
}

void siftUp (queue *q, int i)
{
	if (0 == i)
		return;

	int p = (i - 1) / 2;

	if (q->root[p].priority < q->root[i].priority)
		return;

	q->index[q->root[i].value] = p;
	q->index[q->root[p].value] = i;

	item swap = q->root[i];
	q->root[i] = q->root[p];
	q->root[p] = swap;

	return siftUp (q, p);
}

void insert (queue *q, int value, double pri)
{
	item i;
	i.value = value;
	i.priority = pri;

        int newAllocated = smallestPowerOfTwoAfter ((value + 1) * sizeof(int));

        if ((value + 1) * sizeof (int) > q->indexAllocated) {
		q->index = realloc (q->index, newAllocated);
		if (NULL == q->index)
			exit (1);
		for (unsigned int j = q->indexAllocated / sizeof (int); j < newAllocated / sizeof (int); j++)
			q->index[j] = -1;
		q->indexAllocated = newAllocated;
	}

	int p = placeAtEnd (q, i);

	q->index[q->root[p].value] = p;

	siftUp (q, p);
}

void siftDown (queue *q, int i)
{
	int c = 1 + 2 * i;
	if (c >= q->size)
		return;

	if ((c + 1 < q->size) && (q->root[c].priority > q->root[(c+1)].priority))
		c++;

	if (q->root[i].priority < q->root[c].priority)
		return;

	q->index[q->root[c].value] = i;
	q->index[q->root[i].value] = c;

	item swap = q->root[i];
	q->root[i] = q->root[c];
	q->root[c] = swap;

	return siftDown (q, c);
}

void deleteMin (queue *q)
{
	if (0 == q->size)
		return;

	q->index[q->root[0].value] = -1;
	q->size--;

	if (0 == q->size)
		return;

	q->index[q->root[q->size].value] = 0;
	q->root[0] = q->root[q->size];

	siftDown (q, 0);
}

item *findMin (const queue *q)
{
	return q->root;
}

void changePriority (queue *q, int ind, double newPriority)
{
	int oldPriority = q->root[q->index[ind]].priority;
	q->root[q->index[ind]].priority = newPriority;
	if (oldPriority < newPriority)
		siftDown (q, q->index[ind]);
	else if (oldPriority > newPriority)
		siftUp (q, q->index[ind]);
}

void delete (queue *q, int ind)
{
	changePriority (q, ind, INT_MIN);
	deleteMin (q);
}

int priorityOf (const queue *q, int ind)
{
	return q->root[q->index[ind]].priority;
}

int exists (const queue *q, int ind)
{
	return  (q->indexAllocated / sizeof (int) > ind) &&
		(-1 != q->index[ind]) &&
		(q->size > q->index[ind]);
}

queue* createQueue ()
{
	queue *rv = (queue*) malloc (sizeof (queue));
	if (NULL == rv)
		exit (1);
	rv->size = 0;
	rv->allocated = 0;
	rv->root = NULL;
	rv->index = NULL;
	rv->indexAllocated = 0;
	return rv;
}

void freeQueue (queue* q)
{
	free (q->root);
	free (q->index);
	free (q);
}