But using StringBuilder increases space complexity. Your code has space complexity O(N). Where N is length of string. If you simply print it took O(1).

I agree with your point. Although using StringBuilder will increase the space complexity, but just printing out the result is meanless, that is to say, we can see the result string but we cannot access it because it technically does not exist.

Adding more to that, the real system will slow down for the more number of system input/output operation. It is better to use buffering mechanism to avoid unnecessary output which just slow down the system and have no use at all.

in a huffman tree, a parent node will always have 2 child as we begin by combining 2 nodes and repeat it untill we are done. due to this property, we can safely say that if either of the left or right pointer is null, the other one is also null, and hence it is a leaf node.

Hello, I agree with you that is not going to dramatically improve the performance; but I think are goal is to always try to find the better solutions and even nanosecods matter. Also is just one more line. I ran some test and it actually helps the performace a little.

******This is the code ************

public class StringLength {

public static void usingLengthMethod(String s){
    for(int i = 0; i< s.length();i++){
        ;
    }
}

public static void whithoutLengthMethod(String s){
    int limit = s.length();
    for(int i = 0; i < limit;i++){
        ;
    }
}

public static void main(String [] args){
    long startTime,endTime;
    String s ="Un lago en el cielo quiero ser suave para evitar tu dureza  apago tu fuego enciende"
            +"mi agua puede que no haya certezas Vamos despacio para el tiempo es arena en mis manos sé por tus marcas" 
            +"cuanto has amado más de lo que prometiste";


    startTime = System.nanoTime();
    whithoutLengthMethod(s);
    endTime = System.nanoTime(); 
    System.out.println("Declaring Size: " + (endTime - startTime) + "  nano Seconds");


    startTime = System.nanoTime();
    usingLengthMethod(s);
    endTime = System.nanoTime();
     System.out.println("Using Length() method: " + (endTime - startTime) + "  nano Seconds");
}

}

****RESULTS USING TERMINAL********

Test 1:

Declaring Size: 5480 nano Seconds

Using Length() method: 9196 nano Seconds

Test 2:

Declaring Size: 5021 nano Seconds

Using Length() method: 6803 nano Seconds

Test 3:

Declaring Size: 5144 nano Seconds

Using Length() method: 6887 nano Seconds

Do you realize this section is for discussions, you are not helping or asking a question relating to the problem. To answer your question, the necesary in order to fully understand the problem and realize I was wrong.

what does the "temp = root " does here in the end

if temp.right==None and temp.left==None:
            string.append(temp.data)
            temp=root  <---this one
    b=''.join(string)
    print b

I have tried that someone's approach it worked.only difference is sysout :( .. I didnt debug becoz for this code since the prerequisite is to create a huffman tree.Even I tried that(didnt check online readymade huffman tree code,I implemented huffman tree bymyself),but I couldn't build proper huffman tree. But yeah I have learnt the concept and tried by myself.Yet I am still surprised why that one single thing made difference.I agree with you,even I debug rather than commenting here.But as I said the prerequisite code is not properly setup in my IDE so I didnt debug to the fullest. Thanks anyway.I appreciate your response.

yedava chusko ra