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MinBinaryHeap.java
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MinBinaryHeap.java
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package com.huffman;
public class MinBinaryHeap {
private HuffmanTreeNode[] heap;
private int size;
private int capacity;
private static final int TOP = 1;
static final String code_table = "";
public MinBinaryHeap(HuffmanTreeNode[] aheapStorage) {
this.heap = new HuffmanTreeNode[aheapStorage.length + 1];
heap[TOP] = null;
this.size = aheapStorage.length;
capacity = size;
System.arraycopy(aheapStorage, 0, heap, 1, size);
buildHeap(size);
}
private void buildHeap(int asize) {
for (int i = getParent(asize); i >= TOP; i--) {
heapifyUp(i);
}
}
public HuffmanTreeNode extractMin() {
HuffmanTreeNode result = heap[TOP];
heap[TOP] = heap[size];
heap[size] = null;
size--;
heapifyUp(TOP);
return result;
}
public void insertItem(HuffmanTreeNode item) {
if (size < capacity) {
heap[++size] = item;
int current = size;
while (isValid(current) && isValid(getParent(current)) && heap[getParent(current)].getFrequency() > heap[current].getFrequency()) {
swapTwoValues(getParent(current), current);
current = current / 2;
}
} else {
System.out.println("cannot insert : no space left");
}
}
private void heapifyUp(int index) {
int leftChildIdx = getLeftChild(index);
int rightChildIdx = getRightChild(index);
int smallestIdx = leftChildIdx;
if (isValid(rightChildIdx)) {
if (heap[rightChildIdx].getFrequency() < heap[leftChildIdx].getFrequency()) {
smallestIdx = rightChildIdx;
}
}
if (isValid(smallestIdx)&& heap[smallestIdx].getFrequency() < heap[index].getFrequency()) {
swapTwoValues(smallestIdx, index);
heapifyUp(smallestIdx);
}
}
private void swapTwoValues(int smallestIdx, int index) {
HuffmanTreeNode temp = heap[smallestIdx];
heap[smallestIdx] = heap[index];
heap[index] = temp;
}
private boolean isValid(int index) {
return index >= TOP && index <= size;
}
private int getParent(int index) {
return index / 2;
}
private int getLeftChild(int index) {
return 2 * index;
}
private int getRightChild(int index) {
return 2 * index + 1;
}
public int getSize() {
return size;
}
}