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HuffmanCoding.java
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HuffmanCoding.java
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package com.huffman;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;
public class HuffmanCoding {
static final String code_table = "code_table.txt";
public static HashMap<Integer,HashMapNode>hmap=new HashMap<Integer,HashMapNode>();
public static void build_freq_table(String inputFile) throws IOException{
BufferedReader br = new BufferedReader(new FileReader(inputFile));
String line = "";
while((line = br.readLine()) != null) {
String vars[] = line.split(" ");
int var = Integer.parseInt(vars[0]);
if(hmap.containsKey(var)){
HashMapNode node = hmap.get(var);
node.freq = node.freq+1;
hmap.put(var, node);
}
else{
HashMapNode hmn=new HashMapNode();
hmap.put(var,hmn);
}
}
br.close();
}
public static void build_tree_using_binary_heap(){
try{
HuffmanTreeNode treeRoot = null;
HuffmanTreeNode[] nodes = new HuffmanTreeNode[hmap.size()];
int i=0;
for (Map.Entry<Integer,HashMapNode> e : hmap.entrySet()) {
nodes[i] = new HuffmanTreeNode(e.getKey(),e.getValue().freq);
i++;
}
MinBinaryHeap mbheap = new MinBinaryHeap(nodes);
while (mbheap.getSize() != 1) {
HuffmanTreeNode left = mbheap.extractMin();
HuffmanTreeNode right = mbheap.extractMin();
HuffmanTreeNode top = new HuffmanTreeNode(Integer.MAX_VALUE, left.getFrequency()+ right.getFrequency());
top.setLeft(left);
top.setRight(right);
mbheap.insertItem(top);
}
treeRoot = mbheap.extractMin();
BufferedWriter bw = new BufferedWriter(new FileWriter(code_table));
String s="";
makeCodeTable(treeRoot, s,bw);
bw.flush();
}
catch(Exception e){
System.out.println(e.getMessage());
e.printStackTrace();
}
}
public static void build_tree_using_FourAry_heap(){
try{
HuffmanTreeNode treeRoot = null;
HuffmanTreeNode[] nodes = new HuffmanTreeNode[hmap.size()];
int i=0;
for (Map.Entry<Integer,HashMapNode> e : hmap.entrySet()) {
nodes[i] = new HuffmanTreeNode(e.getKey(),e.getValue().freq);
i++;
}
MinFourAryHeap mbheap = new MinFourAryHeap(nodes);
while (mbheap.getSize() != 3) {
HuffmanTreeNode left = mbheap.extractMin();
HuffmanTreeNode right = mbheap.extractMin();
HuffmanTreeNode top = new HuffmanTreeNode(Integer.MAX_VALUE, left.getFrequency()+ right.getFrequency());
top.setLeft(left);
top.setRight(right);
mbheap.insertItem(top);
}
treeRoot = mbheap.extractMin();
BufferedWriter bw = new BufferedWriter(new FileWriter(code_table));
String s="";
makeCodeTable(treeRoot, s,bw);
bw.flush();
}
catch(Exception e){
e.printStackTrace();
}
}
public static void build_tree_using_pairing_heap(){
try{
HuffmanTreeNode treeRoot = null;
HuffmanTreeNode[] nodes = new HuffmanTreeNode[hmap.size()];
int i=0;
for (Map.Entry<Integer,HashMapNode> e : hmap.entrySet()) {
//setting the data and frequency
nodes[i] = new HuffmanTreeNode(e.getKey(),e.getValue().freq);
i++;
}
//HuffmanTree.makeHuffmanTreeAndMakeCodeTable(nodes);
PairingHeap mbheap = new PairingHeap(nodes);
while (mbheap.root.child!=null) {
HuffmanTreeNode left = mbheap.removeMin();
//System.out.println("removed value1 = "+left.getData());
HuffmanTreeNode right = mbheap.removeMin();
//System.out.println("removed value2 = "+right.getData());
//if(right!=null){
HuffmanTreeNode top = new HuffmanTreeNode(Integer.MAX_VALUE, left.getFrequency()+ right.getFrequency());
top.setLeft(left);
top.setRight(right);
mbheap.insertItem(top);
// }
//else{
// treeRoot = left;
// break;
// }
}
treeRoot = mbheap.removeMin();
//System.out.println("calling bw ");
BufferedWriter bw = new BufferedWriter(new FileWriter(code_table));
///////////////////////////////////////////////////////////////////
String s="";
makeCodeTable(treeRoot, s,bw);
/////////////////////////////////////////////////////////////////////
bw.flush();
}
catch(Exception e){
e.printStackTrace();
}
}
public static void makeCodeTable(HuffmanTreeNode root, String code,BufferedWriter bw) throws IOException {
// Assign 0 to left edge and recur
if (root!=null){
//System.out.println("in code table " + root.getData());
//code = code+"0";
makeCodeTable(root.left, code+"0",bw);
if(root.left==null && root.right==null){
int var=root.getData();
bw.write(var + " " + code);
//codeTableHashMap.put(root.getData(), code);
HashMapNode node = hmap.get(var);
node.bits = code;
hmap.put(var, node);
bw.newLine();
}
//code = code+"1";
makeCodeTable(root.right, code+"1",bw);
//System.out.println();
}
}
public static void main(String args[]){
Scanner sc=new Scanner(System.in);
String input_file=sc.next();
try {
HuffmanCoding.build_freq_table(input_file);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
//System.out.println(hmap);
long startTime = System.currentTimeMillis();
build_tree_using_pairing_heap();
long endTime = System.currentTimeMillis();
long totalTime = endTime - startTime;
System.out.println("Time using binary heap (millisecond): " +totalTime);
sc.close();
//hc.convertInputToencoded();
}
public static String convertInputToencoded(String inputFile) throws IOException{
BufferedReader br = new BufferedReader(new FileReader(inputFile));
String line = "";
StringBuilder pText=new StringBuilder();
while((line = br.readLine()) != null) {
String vars[] = line.split(" ");
int var = Integer.parseInt(vars[0]);
HashMapNode node = hmap.get(var);
pText.append(node.bits);
}
br.close();
//this.hmap=hmap;
return pText.toString();
}
}