Hamming Code added

sjs7007 · sjs7007 · commit 400ddd91f64d · 2013-12-24T11:06:43.000+05:30
diff --git a/Hamming_Code/sjs7007_Hamming_Code.java b/Hamming_Code/sjs7007_Hamming_Code.java
@@ -0,0 +1,96 @@
+//Hamming Code 
+import java.util.*;
+
+class sjs7007_Hamming_Code
+{
+	public static void main(String[] args) 
+	{
+		Scanner ip = new Scanner(System.in);
+		System.out.print("Enter Message : ");
+		String msg = ip.next();
+		int r=0,m=msg.length(); 
+		//calculate number of parity bits needed using m+r+1<=2^r
+		while(true)
+		{
+			if(m+r+1<=Math.pow(2,r))
+			{
+				break;
+			}
+			r++;
+		}
+		System.out.println("Number of parity bits needed : "+r);
+		int transLength = msg.length()+r,temp=0,temp2=0,j=0;
+		int transMsg[]=new int[transLength+1]; //+1 because starts with 1
+		for(int i=1;i<=transLength;i++)
+		{
+			temp2=(int)Math.pow(2,temp);
+			if(i%temp2!=0)
+			{
+				transMsg[i]=Integer.parseInt(Character.toString(msg.charAt(j)));
+				j++;
+			}
+			else
+			{
+				temp++;
+			}
+		}
+		for(int i=1;i<=transLength;i++)
+		{
+			System.out.print(transMsg[i]);
+		}
+		System.out.println();	
+
+		for(int i=0;i<r;i++)
+		{
+			int smallStep=(int)Math.pow(2,i);
+			int bigStep=smallStep*2;
+			int start=smallStep,checkPos=start;
+			System.out.println("Calculating Parity bit for Position : "+smallStep);
+			System.out.print("Bits to be checked : ");
+			while(true)
+			{
+				for(int k=start;k<=start+smallStep-1;k++)
+				{
+					checkPos=k;
+					System.out.print(checkPos+" ");
+					if(k>transLength)
+					{
+						break;
+					}
+					transMsg[smallStep]^=transMsg[checkPos];
+				}
+				if(checkPos>transLength)
+				{
+					break;
+				}
+				else
+				{
+					start=start+bigStep;
+				}
+			}
+			System.out.println();
+		}	
+		//Display encoded message
+		System.out.print("Hamming Encoded Message : ");
+		for(int i=1;i<=transLength;i++)
+		{
+			System.out.print(transMsg[i]);
+		}
+		System.out.println();
+	}
+}
+
+/* Output
+
+Enter Message : 1001
+Number of parity bits needed : 3
+0010001
+Calculating Parity bit for Position : 1
+Bits to be checked : 1 3 5 7 9 
+Calculating Parity bit for Position : 2
+Bits to be checked : 2 3 6 7 10 
+Calculating Parity bit for Position : 4
+Bits to be checked : 4 5 6 7 12 
+Hamming Encoded Message : 0011001
+
+*/
