FIles.jav

import java.io.*;
import java.util.Arrays;



public class huffAlgorithm {
	
	
	

   public static void main(String args[]) throws IOException {  
      FileInputStream in = null, in2;
      FileOutputStream out = null;
      
      int [][]  a = new int[2][128];
      
     in = new FileInputStream("test.txt");
     out = new FileOutputStream("output.bin");
     
     int c;
     while ((c = in.read()) != -1)
    	 if(c < 128 && c != 13)
    		 a[0][c]++;
     
    int count = 0;
    
     for(int e = 0;  e < 128; e++)
    	 if(a[0][e] != 0) {
    		 //System.out.printf("%d, %d, (%c)\n",e, a[e], (char) e);
    		 count++;
    	 }
     
     priorityQueue pq0 = new priorityQueue(count);
     	
     for(int e = 0;  e < 128; e++)
    	 if(a[0][e] != 0) {
    		 Node n = new Node((char) e, a[0][e]);
    		 pq0.offer(n);
    	 }
     
     System.out.println(Arrays.toString(pq0.minHeap));
     
     
     //Build huffman tree
     
     while(pq0.size > 1) {
    	 Node p = pq0.poll(); 
    	 Node q = pq0.poll();
    	
    	 Node n = new Node('_', p.w + q.w);
    	 n.left = p;
    	 n.right = q;
    	 pq0.offer(n);
    	 
     }
     
     Node root = pq0.poll();
     
     print(root,0);
     
     int r = 0;
     
    //char[] charArray = new char[64];
    
    encode(root, r, a,0);
    
    
    in.close();
    //read again document and create binary file
    
    in2 = new FileInputStream("test.txt");
    
    
    
    char buffer = 0;
    byte AvailableBits = 7;
    
    while ((c = in2.read()) != -1) {
    	if(c < 128 && c != 13) {
    		int temp = a[0][c];
    		for(int i = 0; i < a[1][c]; i++) {
    			System.out.printf("%d",temp & 1);
    			buffer |= (temp & 1) << AvailableBits;
    			if(--AvailableBits < 0) {
    				out.write(buffer);
    				buffer = 0;
    				AvailableBits = 7;
    			}
    			temp >>= 1;
    		}
    	}
    }	
    
    System.out.println();
   	 
   		 
    System.out.println(Arrays.toString(a[0]));
    //System.out.println(a[0][':']);
    
     
     in2.close();   
     out.close();
         
   }
   
   private static void print(Node node, int spaces) {
		
	   if(node.right != null)print(node.right, spaces + 1);
		
		for(int i = 0; i < spaces; i++)System.out.printf("-");System.out.println(node);
		
		if(node.left != null)print(node.left, spaces + 1);	
		
	}
   
   private static void encode(Node node, int register, int[][] charArray, int length ) {
	   
	   if(node.left == null && node.right == null) {
		   System.out.printf("%d, %c, %d, %d\n",register, node.s, length, reverse(length,register));
		   charArray[0][node.s] = reverse(length,register);
		   charArray[1][node.s] = length;
	   }
		   
	   if(node.left != null)encode(node.left, register << 1, charArray, length + 1);
		
	   if(node.right != null)encode(node.right, (register << 1) | 1, charArray, length + 1);
		
	}
   
   private static int reverse(int n, int reverse) {
	   int aux = reverse;
	   reverse = 0;
	   for(int i = 0; i < n; i++) {
		  // System.out.printf("iteration %d, %d, %d\n",i,reverse,  ((aux >> i) & 1));
		   reverse |= (aux >> i) & 1;
		   reverse <<= 1;
	   }
	   return reverse >> 1;
   }
   

   static class Node implements Comparable<Node>{
	   Node left = null, right = null;
	   int w = 0;
	   char s = 0x00;
	   
	   public Node(char c, int w) {
		   s = c;
		  this.w = w;
	   }

	@Override
	public int compareTo(Node o) {
		return this.w -
				o.w;
	}
	
	@Override
	public String toString() {
		//return String.format("%d, %d, (%c)\n",(int)s, w, s);
		return String.format("%d, (%c)\n", w, s);
		
	}
   }
   
   static class priorityQueue {
	   int capacity = 0;
	   int size = 0;
	   Node[] minHeap;
	   
	   public priorityQueue(int c) {
		   this.capacity = c;
		   this.minHeap = new Node[this.capacity];
	   }
	   
	   public void offer(Node e) {
		   int index = size;
		   minHeap[index] = e;
		   
		   
		   while(minHeap[index].compareTo(minHeap[(index - 1) / 2]) < 0 && index != 0){
			   Node temp = minHeap[(index - 1) /  2];
			   minHeap[(index - 1) / 2] = minHeap[index];
			   minHeap[index] = temp;
			   index = (index - 1) / 2;
		   }	   
			size++;
	   }
	   
	   
	   public int min(int index) {
		   index <<= 1;
		   if(index + 1 >= size) return size;
		   if(index + 2 >= size) return index + 1;
		   return minHeap[index + 1].compareTo(minHeap[index + 2]) <= 0 ? index + 1 : index + 2;
	   }
	   
	   public Node poll() {
		   Node root = minHeap[0];
		   minHeap[0] = minHeap[size - 1];
		   int index = 0;
		   
		   int smallest = min(index);
		   
		   
		   while(minHeap[index].compareTo(minHeap[smallest]) > 0) {
			   Node temp = minHeap[smallest];
			   minHeap[smallest] = minHeap[index];
			   minHeap[index] = temp;
			   index = smallest;
			   smallest = min(index);
			   if(smallest >= size) break;
		   }
		   
		   size--;
		   return root;
	   }
	   
	   public Node peek() {
		   return minHeap[0];
	   }
   }
}

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