Programming interview - written tests

[D_Mad]

good thread

 

[C h o p p e]

බ්ම්ප්

 

[ArnoDorian]

Reverse String in Java

Reverse a given String in java without StringBuffer/Builder..
Intern Technical interview @ Virtusa

 

[elektro]

Reverse a given String in java without StringBuffer/Builder..
Intern Technical interview @ Virtusa

ela macho

 

[elektro]

do some hackerrank and codility tests for algo related questions.

thanx ayya..I'm doing too..

 

[shw7]

Reverse a given String in java without StringBuffer/Builder..
Intern Technical interview @ Virtusa

class riverse{
public static void main(String args[]){

String word = "Test";
//riverse = riverse(word);
System.out.println(riverse(word));
}

public static String riverse(String source){

String riverse= "";
for(int i= source.length() - 1; i>=0; i--){
riverse = riverse + source.charAt(i);
}
return riverse;
}
}

 

[Capital_M]

TFS

 

[EMINƎM]

class riverse{
public static void main(String args[]){

String word = "Test";
//riverse = riverse(word);
System.out.println(riverse(word));
}

public static String riverse(String source){

String riverse= "";
for(int i= source.length() - 1; i>=0; i--){
riverse = riverse + source.charAt(i);
}
return riverse;
}
}

how do we optimize this code?

class riverse{
    public static void  main(String args[]){
    
        String word = "Test";
        //riverse = riverse(word);
        System.out.println(riverse(word));
    }
    
    public static String riverse(String source){
    
        StringBuilder  riverse= new StringBuilder("");
        
        for(int i = source.length()-1; i>=0; i--) {
             riverse.append(source.charAt(i));
        }

         return  riverse.toString();
    }
}

changing "riverse" String to a StringBuilder so that it wont fill up the String constant pool every time when the "for loop" continues
Since String is an immutable and StringBuilder is not, StringBulder can append to the same object in the memory every time, which takes less memory space





how to change the code to test a palindrome?

class riverse{
    public static void  main(String args[]){
    
        String word = "sourcecruos";
        //riverse = riverse(word);
        System.out.println(riverse(word));
    }
    
    public static boolean riverse(String source){
    
        StringBuilder  riverse= new StringBuilder("");
        
        for(int i = source.length()-1; i>=0; i--) {
             riverse.append(source.charAt(i));
        }

         return  source.equals(reversedString.toString());
    }
}

 

[saja]

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[thinking_guy]

Swap two numbers stored in two integer variables without using a third variable.

 

[saja]

owa nam gemak na

var a = 10, b = 20;

a = a + b;
b = a - b;
a = a - b;

output balanna run karala

Swap two numbers stored in two integer variables without using a third variable.

 

[windows_ubuntu]

owa nam gemak na

var a = 10, b = 20;

a = a + b;
b = a - b;
a = a - b;

output balanna run karala

then how to get value of b(after swaping)

 

[thinking_guy]

owa nam gemak na

var a = 10, b = 20;

a = a + b;
b = a - b;
a = a - b;

output balanna run karala

Then swap two strings with out using a third variable.

 

[EMINƎM]

owa nam gemak na

var a = 10, b = 20;

a = a + b;
b = a - b;
a = a - b;

output balanna run karala

Is there any other method to swap the variables without using +,-,* or / ?

 

[EMINƎM]

Then swap two strings with out using a third variable.

String a = "thinking";
String b = "guy";

a = a + b; //thinkingguy
b = a.substring(0, a.length()-b.length()); //thingking
a = a.substring(b.length()); //guy

System.out.println("a " + a);
System.out.println("b " + b);

 

[thinking_guy]

String a = "thinking";
String b = "guy";

a = a + b; //thinkingguy
b = a.substring(0, a.length()-b.length()); //thingking
a = a.substring(b.length()); //guy

System.out.println("a " + a);
System.out.println("b " + b);

You are hired son.

 

[thinking_guy]

Is there any other method to swap the variables without using +,-,* or / ?

Xor swapping

 

[EMINƎM]

You are hired son.

Xor swapping

 

[saja]

look here carefully

if a = 10, b = 20;

a = a + b; -- line 01
b = a - b; -- line 02
a = a - b; -- line 03

-- line 01 output a = a + b = 10+ 20 = 30 , (still b = 20)
-- line 02 output b = a - b = 30 - 20 = 10, (still a = 30)
-- line 03 output a = a - b = 30 - 10 = 20

final output a = 20 , b = 10

still cannot understand

this is valid and no need for Xor swapping

then how to get value of b(after swaping)

 

[windows_ubuntu]

look here carefully

if a = 10, b = 20;

a = a + b; -- line 01
b = a - b; -- line 02
a = a - b; -- line 03

-- line 01 output a = a + b = 10+ 20 = 30 , (still b = 20)
-- line 02 output b = a - b = 30 - 20 = 10, (still a = 30)
-- line 03 output a = a - b = 30 - 10 = 20

final output a = 20 , b = 10

still cannot understand

this is valid and no need for Xor swapping

understood. thanx brother