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IndexHeapReverse.java
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199 lines (155 loc) · 4.64 KB
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public class IndexHeapReverse<Key extends Comparable<Key>> {
// 最大索引堆
/*
* indexes[i] = j
* reverse[j] = i
*
* indexes[reverse[i]] = i
* reverse[indexes[i]] = i
*
* */
private Key[] data;
private int capacity;
int[] indexes;
int[] reverse;
private int count;
public int size() {
return count;
}
public boolean isEmpty() {
return count == 0;
}
public IndexHeapReverse(int capacity) {
data = (Key[]) new Comparable[capacity + 1];
indexes = new int[capacity + 1];
reverse = new int[capacity + 1];
for (int i = 0; i <= capacity; i++) {
// 从 1 开始，因此 0 为非法索引
reverse[i] = 0;
}
count = 0;
this.capacity = capacity;
}
private boolean less(int i, int j) {
return data[i].compareTo(data[j]) < 0;
}
private void exch(int i, int j) {
Key tmp = data[i];
data[i] = data[j];
data[j] = tmp;
}
private void exchIndex(int i, int j) {
int tmp = indexes[i];
indexes[i] = indexes[j];
indexes[j] = tmp;
/*// 此时 indexes i和j 已经发生了交换，所以只需要如下编写即可
reverse[indexes[i]] = i;
reverse[indexes[j]] = j;*/
}
public void swin(int k) {
// 上浮
while (k > 1 && less(indexes[k / 2], indexes[k])) {
// exch(k / 2, k);
exchIndex(k / 2, k);
// reverse 维护
// 此时 indexes k和k/2 已经发生了 改变，所以只需要如下编写即可
reverse[indexes[k / 2]] = k / 2;
reverse[indexes[k]] = k;
k = k / 2;
}
}
public void sink(int k) {
// 下沉
while (k * 2 <= count) {
int j = k * 2;
if (j < count && less(indexes[j], indexes[j + 1])) j++;
if (!less(indexes[k], indexes[j])) break;
// exch(indexes[k], indexes[j]);
exchIndex(k, j);
// reverse 维护
reverse[indexes[k]] = k;
reverse[indexes[j]] = j;
k = j;
}
}
// 传入的i对用户而言，是从0索引的
public void insert(int i, Key key) {
assert (count + 1 <= capacity);
assert (i + 1 >= 1 && i + 1 <= capacity);
i += 1;
data[i] = key;
indexes[count + 1] = i;
// reverse 维护
reverse[i] = count + 1;
count++;
swin(count);
}
public Key delMax() {
assert (count > 0);
Key key = data[indexes[1]];
// exch(indexes[1], indexes[count]);
exchIndex(1, count);
// reverse 维护
reverse[indexes[1]] = 1;
reverse[indexes[count]] = 0; // 因为是删除操作
count--;
sink(1);
return key;
}
public int delMaxIndex() {
assert (count > 0);
int ret = indexes[1] - 1;
// exch(indexes[1], indexes[count]);
exchIndex(1, count);
// reverse 维护
reverse[indexes[1]] = 1;
reverse[indexes[count]] = 0; // 因为是删除操作
count--;
sink(1);
return ret;
}
// 从 1 开始，因此 0 为非法索引
private boolean contain(int i) {
if (!(i + 1 >= 1 && i + 1 <= capacity))
throw new RuntimeException("Error");
return reverse[i + 1] != 0;
}
public Key getKey(int i) {
// assert( contain(i) )
if (!contain(i))
throw new RuntimeException("Error");
return data[i + 1];
}
public void change(int i, Key newKey) {
// assert( contain(i) )
if (!contain(i))
throw new RuntimeException("Error");
i += 1;
data[i] = newKey;
// 找到 indexes[j] = i, j表示data[i]在堆中的位置
// 找到之后 swin(j)，再 sink(j)
// for (int j = 1; j <= count; j++) {
// if (indexes[j] == i) {
// swin(j); // 上移
// sink(j); // 下沉
// return;
// }
// }
int j = reverse[i];
swin(j);
sink(j);
}
private void sort(Comparable a[]) {
}
public static void main(String[] args) {
int[] nums = {3, 6, 2, 4, 5, 1};
IndexHeapReverse<Integer> maxHeap = new IndexHeapReverse<>(nums.length);
for (int i = 0; i < nums.length; i++) {
maxHeap.insert(i, nums[i]);
}
for (int i = 0; i < nums.length; i++) {
System.out.println(maxHeap.delMax());
// System.out.println(maxHeap.delMaxIndex());
}
}
}