public void testChangePriority() {
PriorityQueue q = new MinHeap(N);
Item items[] = new Item[N];
for (int i = 0; i < N; i++) {
Item e = new Item(N - i - 1);
q.insert(e);
items[i] = e;
}
q.changePriority(items[N - 1], -2);
q.changePriority(items[N / 2], -1);
q.changePriority(items[N / 2 + 1], N * 2);
int j = 0;
double pr_last = Double.NEGATIVE_INFINITY;
assertTrue("descending size", q.size() == N);
while (q.size() > 0) {
assertTrue("descending extract", j < N);
QueueElement e = q.extractMin();
assertTrue("descending order", e.getPriority() > pr_last);
pr_last = e.getPriority();
if (j == 0) assertTrue("lowest elt", e.getPriority() == -2);
if (j == 1) assertTrue("second-lowest elt", e.getPriority() == -1);
if (q.size() == 1) assertTrue("penultimate elt", e.getPriority() == N - 1);
if (q.size() == 0) assertTrue("final elt", e.getPriority() == N * 2);
j++;
}
}
public void testReverse() {
PriorityQueue q = new MinHeap(N);
Item items[] = new Item[N];
for (int i = 0; i < N; i++) {
Item e = new Item(N - i - 1);
q.insert(e);
items[i] = e;
}
for (int i = 0; i < N; i++) {
q.changePriority(items[i], i);
}
int j = 0;
double pr_last = Double.NEGATIVE_INFINITY;
assertTrue("ascending size", q.size() == N);
while (q.size() > 0) {
assertTrue("ascending extract", j < N);
QueueElement e = q.extractMin();
assertTrue("ascending order", e.getPriority() > pr_last);
pr_last = e.getPriority();
assertEquals("ascending priority", items[j].getPriority(), e.getPriority());
assertEquals("ascending identity", items[j], e);
j++;
}
}
