added huffmann coding

Author: getsanjeev

greedy/huffman.java

@@ -0,0 +1,155 @@
+package sorting;
+
+/**
+ * Created by sanjeev on 4/2/17.
+ */
+public class huffman
+{
+    public static void main(String [] args)
+    {
+        System.out.println("Welcome to Huffman");
+        int [] array = utility.input_for_sorting();
+        new huffman().get_huffman_codes(array);
+        //utility.print_array(array);
+    }
+
+    int [] get_huffman_codes(int [] array)
+    {
+        int min1,min2,sum;
+        boolean first = true;
+        build_min_heap(array);
+        System.out.println("The min heap is: ");
+        utility.print_array(array);
+        min1 = extract_min(array,true);
+        first = false;
+        min2 = extract_min(array,first);
+        sum = min1+min2;
+        insert(array,sum);
+        utility.print_array(array);
+        for(int i =1;i<array.length-1;i++)
+        {
+            min1 = extract_min(array,first);
+            min2 = extract_min(array,first);
+            sum = min1+min2;
+            insert(array,sum);
+            utility.print_array(array);
+        }
+        return array;
+    }
+
+    void insert(int [] array, int value)
+    {
+        int temp;
+        int index = array[array.length -1];
+        index++;
+        array[index] = value;
+        array[array.length -1]++;
+        int parent = index;
+        while(parent>0)
+        {
+            if (index%2==0) parent = (index -2)/2;
+            else parent = (index-1)/2;
+            //System.out.println("parent " + parent);
+            if(array[parent] > array[index])
+            {
+                temp = array[parent];
+                array[parent] = array[index];
+                array[index] = temp;
+                index = parent;
+            }
+            else break;
+        }
+    }
+
+    int extract_min(int [] array, boolean first)
+    {
+        //System.out.println("PRINTING IN EXTRACT MIN");
+        int temp = array[0];
+        if(first)
+        {
+            array[0] = array[array.length-1];
+            array[array.length -1] = array.length -2;
+        }
+        else
+        {
+            array[0] = array[array[array.length-1]];
+          //  System.out.println(array[array.length-1] + "index prv for min haeaify");
+            array[array.length-1] --;
+            //System.out.println(array[array.length-1] + "index for min haeaify");
+        }
+        min_heapify(array,0,array[array.length-1]);
+        return temp;
+    }
+
+    public void min_heapify(int [] array,int i, int j)
+    {
+        //System.out.println("incoming value " + i + " " + j);
+        int min_index ;
+        int left = 2*i+1;
+        //System.out.println(left + "left" + (array.length - j));
+        int right = 2*i+2;
+        //System.out.println(right + "right" + (array.length - j));
+        if(left <= j)
+        {
+            if(right <= j)
+            {
+                if(array[left] < array[right])  min_index = left;
+                else min_index = right;
+                if((array[i] < array[min_index])) min_index = i;
+            }
+            else
+            {
+                if (array[i] > array[left])
+                min_index = left;
+                else min_index = i;
+            }
+          //  System.out.println("values" + min_index + " " + i);
+            if(min_index!=i)
+            {
+          //      System.out.println("in the not equal loop");
+                int temp = array[i];
+                array[i] = array[min_index];
+                array[min_index] = temp;
+                min_heapify(array,min_index,j);
+            }
+        }
+
+    }
+
+    public void min_heapify(int [] array,int i)
+    {
+        int min_index ;
+        int left = 2*i+1;
+        int right = 2*i+2;
+        if(left < array.length)
+        {
+            if(right < array.length)
+            {
+                if(array[left] < array[right])  min_index = left;
+                else min_index = right;
+                if((array[i] < array[min_index])) min_index = i;
+            }
+            else
+            {
+                min_index = left;
+            }
+            if(min_index!=i)
+            {
+                int temp = array[i];
+                array[i] = array[min_index];
+                array[min_index] = temp;
+                min_heapify(array,min_index);
+            }
+        }
+    }
+
+    public void build_min_heap(int [] array)
+    {
+        for(int i= (array.length/2) - 1;i>=0;i--)
+        {
+            min_heapify(array,i);
+        }
+    }
+
+
+}

greedy/utility.java

@@ -0,0 +1,41 @@
+package sorting;
+
+import java.util.Scanner;
+
+/**
+ * Created by sanjeev on 19/12/16.
+ */
+public class utility
+{
+    public static void print_array(int [] array)
+    {
+        for(int i= 0;i<array.length;i++)
+        {
+            System.out.print(array[i]+" ");
+        }
+        System.out.println();
+    }
+
+
+    public static void print_array(String [] array)
+    {
+        for(int i= 0;i<array.length;i++)
+        {
+            System.out.println(array[i]);
+        }
+    }
+
+    public static int [] input_for_sorting()
+    {
+        System.out.println("Enter the size of array.");
+        Scanner alpha = new Scanner(System.in);
+        int size = alpha.nextInt();
+        int [] array = new int [size];
+        System.out.println("Enter the numbers.");
+        for(int i = 0;i<size;i++)
+        {
+            array[i] = alpha.nextInt();
+        }
+        return array;
+    }
+}