.

.

java-guava-playground/src/main/java/com/github/diegopacheco/sandbox/java/bigonotations/BigONotationOn.java

@@ -0,0 +1,48 @@
+package com.github.diegopacheco.sandbox.java.bigonotations;
+
+public class BigONotationOn {
+
+	private static int[] theArray = new int[1000];
+	private static int sizeOfArray = 0;
+
+	public static void main(String[] args) {
+
+		oNBigONotation(60,1);
+		oNBigONotation(60,100);
+		oNBigONotation(60,1000);
+		oNBigONotation(60,100000);
+		oNBigONotation(60,10000000);
+
+	}
+
+	//
+	// O(n) -> Linear Search -> the operation time will be proporsional of the number of elements of the array.
+	//
+	private static void oNBigONotation(int value,int size){
+		long init = System.currentTimeMillis();
+		theArray =  new int[size];
+		randomValues(size);
+
+		boolean found = false;
+		String index = "";
+
+		for(int i=0;i < (sizeOfArray-1) ; i++){
+			if(theArray[i]==value){
+				found = true;
+				index += i + " ";
+			}
+		}
+		System.out.println("Result Result: " + found);
+		System.out.println("Linear Search in the Array : " + (System.currentTimeMillis()-init)  + " ms" );
+
+		sizeOfArray = 0;
+	}
+
+	private static void randomValues(int n){
+		for(int i=0; i < (n-1) ;i++){
+			sizeOfArray++;
+			theArray[i] =  new Double((Math.random() * 1000)).intValue();
+		}
+	}
+
+}

java-guava-playground/src/main/java/com/github/diegopacheco/sandbox/java/bigonotations/BigONotationOone.java

@@ -0,0 +1,26 @@
+package com.github.diegopacheco.sandbox.java.bigonotations;
+
+public class BigONotationOone {
+
+	private static int[] theArray = new int[1000];
+	private static int itemsOfArray = 0;
+
+	public static void main(String[] args) {
+		oOneBigONotation(1,1);
+		oOneBigONotation(13,1000);
+		oOneBigONotation(60,10000);
+	}
+
+	//
+	// O(1) -> Add One Item to the Array -> No matter the size of the array the operation time is constant.
+	//
+	private static void oOneBigONotation(int newItem,int size){
+		long init = System.currentTimeMillis();
+		theArray = new int[size];
+		theArray[itemsOfArray++] = newItem;
+		System.out.println("Add item Array Took : " + (System.currentTimeMillis()-init)  + " ms" );
+	}
+
+
+
+}

java-guava-playground/src/main/java/com/github/diegopacheco/sandbox/java/md5/MD5HashFun.java

@@ -0,0 +1,33 @@
+package com.github.diegopacheco.sandbox.java.md5;
+
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+
+public class MD5HashFun {
+
+	private static MessageDigest md = null;
+	static{
+		try {
+			md = MessageDigest.getInstance("MD5");
+		} catch (NoSuchAlgorithmException e) {
+			throw new RuntimeException(e);
+		}
+	}
+
+	public static void main(String[] args) {
+		long init = System.currentTimeMillis();
+		String hash = hashIt(java.util.UUID.randomUUID().toString());
+		System.out.println("Hash Took : " + (System.currentTimeMillis()-init)  + " ms" );
+		System.out.println("Hash: "  + hash);
+	}
+
+	private static String hashIt(String base){
+		md.update(base.getBytes());
+		byte byteData[] = md.digest();
+		StringBuffer sb = new StringBuffer();
+        for (int i = 0; i < byteData.length; i++) {
+         sb.append(Integer.toString((byteData[i] & 0xff) + 0x100, 16).substring(1));
+        }
+        return sb.toString();
+	}
+}