A-M baby

Task/Gray-code/Java/gray-code-1.java

@@ -0,0 +1,21 @@
+public class Gray {
+	public static long grayEncode(long n){
+		return n ^ (n >>> 1);
+	}
+	
+	public static long grayDecode(long n) {
+		long p = n;
+		while ((n >>>= 1) != 0)
+			p ^= n;
+		return p;
+	}
+	public static void main(String[] args){
+		System.out.println("i\tBinary\tGray\tDecoded");
+		for(int i = -1; i < 32;i++){
+			System.out.print(i +"\t");
+			System.out.print(Integer.toBinaryString(i) + "\t");
+			System.out.print(Long.toBinaryString(grayEncode(i))+ "\t");
+			System.out.println(grayDecode(grayEncode(i)));
+		}
+	}
+}

Task/Gray-code/Java/gray-code-2.java

@@ -0,0 +1,12 @@
+public static long grayEncode(long n){
+	long result = 0;
+	for(int exp = 0; n > 0; n /= 2, exp++){
+		long nextHighestBit = (n >> 1) & 1;
+		if(nextHighestBit == 1){
+			result += ((n & 1) == 0) ? (1 << exp) : 0; //flip the bit
+		}else{
+			result += (n & 1) * (1 << exp); //"n & 1" is "this bit", don't flip it
+		}
+	}
+	return result;
+}

Task/Gray-code/Java/gray-code-3.java

@@ -0,0 +1,11 @@
+public static BigInteger grayDecode(BigInteger n){
+	String nBits = n.toString(2);
+	String result = nBits.substring(0, 1);
+	for(int i = 1; i < nBits.length(); i++){
+		//bin[i] = gray[i] ^ bin[i-1]
+
+		//XOR with characters
+		result += nBits.charAt(i) != result.charAt(i - 1) ? "1" : "0";
+	}
+	return new BigInteger(result, 2);
+}