[Numbers] Compare Version Numbers

1. Example


0.1 < 1.1 return -1; // like Comparable Class's Comparator's public int compare method, ascending -1
1.2 > 1.1 return 1;// descending , 1
13.37 == 13.37 return 0


2. Implementation
Q1: How to compare if there is a decimal point?
A1: split into two parts from decimal point, then compare the first part if first part is equal, proceed to second part if we have second part




Input:"1", "1.1"
Output:0
Expected:-1

One is len 2 and the other is len 1

which will not compare the second one if len is not balanced

Input:"1.0", "1"
Output:1
Expected:0

Runtime Error Message:Line 102: java.lang.ArrayIndexOutOfBoundsException: 1
Last executed input:"1", "1.0"

Input:"10.6.5", "10.6"
Output:0
Expected:1

// NOTE: dot is a special char in regexes, So you must escape it with a leading backslash, But the leading backslash is a special character, So it must be escaped too, with another leading backslash 

It means "match all chars except newlines"

 String[] v1Arr = v1.split("\\."); 

 String[] v2Arr = v2.split("\\.");

// NOTE: may have more than one decimal point 

 while ( index < v1Arr.length || index < v2Arr.length ) {


// NOTE: same length 

 if ( index < v1Arr.length && index < v2Arr.length) {


// NOTE: v1 longer 

 else if ( index < v1Arr.length ) {

 if ( Integer.parseInt(v1Arr[index]) != 0 ) return 1; } 

 // NOTE: v2 longer 

 else if ( index < v2Arr.length ) {

 if ( Integer.parseInt(v2Arr[index]) != 0 ) return -1; } 

// time:O(length of splitted arry), Space:O(n) array
public int compareVerison(String v1, String v2)
{
        




       // validate the input
       if ( v1== null && v2 == null )
            return 0;
       if ( v1== null || v1.length()==0 )
            return -1;
       if ( v2 ==null || v2.length() == 0)
            return 1;


 

       // http://docs.oracle.com/javase/7/docs/api/java/lang/String.html 
       v1.trim();
       v2.trim();
       // NOTE: Line 75: error: incompatible types: char cannot be converted to String
       //String[] v1Arr = v1.split('.');
       //String[] v2Arr = v2.split('.');
       //String[] v1Arr = v1.split(".");
       //String[] v2Arr = v2.split(".");
       //http://stackoverflow.com/questions/13460595/using-string-split-with-a-decimal-not-working
       // NOTE: dot is a special char in regexes(It means "match all chars except newlines"), So you must escape it with a leading backslash, But the leading backslash is a special character,  So it must be escaped too, with another leading backslash
       String[] v1Arr = v1.split("\\.");
       String[] v2Arr = v2.split("\\.");
       // You may assume that the version strings are non-empty and contain only digits and the . character. 
       // No need to worry no '.'
       int index = 0;
       //while ( index < v2Arr.length && index < v1Arr.length  )
       // NOTE: may have more than one decimal point
       while (  index < v1Arr.length || index < v2Arr.length )
       {              
             // NOTE:http://docs.oracle.com/javase/7/docs/api/java/lang/Integer.html
             //int v1Value = Integer.valuesOf( v1Arr[index]);
             //int v2Value = Integer.valuesOf( v2Arr[index]);
             //int v1Value = Integer.valueOf( v1Arr[index]);
             //int v2Value = Integer.valueOf( v2Arr[index]);
             //if (  v1Value < v2Value )
             //      return -1;
             //else if ( v1Value > v2Value )
             //      return 1;
             //else 
             //{
             //      if (index ==1)
             //          return 0;
             //}
             // NOTE: same length
             if ( index < v1Arr.length && index < v2Arr.length)
             {
                  if (  Integer.parseInt(v1Arr[index]) < Interger.parseInt(v2Arr[index])  ) 
                     return -1;
                  else if ( Integer.parseInt(v1Arr[index]) > Integer.parseInt(v2Arr[index]) )
                     return 1;
             }
             // NOTE: v1 longer
             else if ( index < v1Arr.length ) 
             {
                  if ( Integer.parseInt(v1Arr[index]) != 0 )
                       return 1;   
             }
             // NOTE: v2 longer
             else if ( index < v2Arr.length )
             {
                  if (  Integer.parseInt(v2Arr[index]) != 0 )
                       return -1;
             }


             index++;

       }





       return 0;
       



}

3. Similar ones
Comparable Class Comparator