HackerRank: Manasa and Stones


Manasa is out on a hike with friends. She finds a trail of stones with numbers on them. She starts following the trail and notices that two consecutive stones have a difference of either a or b. Legend has it that there is a treasure trove at the end of the trail and if Manasa can guess the value of the last stone, the treasure would be hers. Given that the number on the first stone was 0, find all the possible values for the number on the last stone.

Note: The numbers on the stones are in increasing order.

Input Format
The first line contains an integer T, i.e. the number of test cases. T test cases follow; each has 3 lines. The first line contains nn (the number of stones). The second line contains a, and the third line contains b.

Output Format
Space-separated list of numbers which are the possible values of the last stone in increasing order.


Sample Input


Sample Output

2 3 4 
30 120 210 300 


All possible series for the first test case are given below:

  1. 0,1,2
  2. 0,1,3
  3. 0,2,3
  4. 0,2,4

Hence the answer 2 3 4.

Series with different number of final steps for second test case are the following:

  1. 0, 10, 20, 30
  2. 0, 10, 20, 120
  3. 0, 10, 110, 120
  4. 0, 10, 110, 210
  5. 0, 100, 110, 120
  6. 0, 100, 110, 210
  7. 0, 100, 200, 210
  8. 0, 100, 200, 300

Hence the answer 30 120 210 300.


Original solution source

HackerRank: CodeWhiz.java March 2016: Serve the Students


In this problem, there are 22 types of events: ENTER (a student enters the queue) or SERVED.

A unique token is assigned to any student entering the queue. The queue serves the students based on the following criteria:

  1. The student having the highest Cumulative Grade Point Average (CGPA) is served first.
  2. Any students having the same CGPA will be served by name in ascending case-sensitive alphabetical order.
  3. Any students having the same CGPA and name will be served in ascending token order.

Given a sequence of nn events, print the names of students who are yet to be served(based on above criteria). If the queue is empty, print EMPTY.

Input Format

The first line of input contains an integer, nn, denoting the total number of events. Each of the nn subsequent lines will be of the following two forms:

  1. ENTER name CGPA token – The student to be inserted into the priority queue.
  2. SERVED – The highest priority student in the queue was served.


  • 2n1000
  • 0CGPA4.00 where CGPAR
  • 1token(i)10where each token(i) is a unique integer.
  • 2|name|30

Output Format

Print the names (based on the criteria) of the students who are not served at all after executing all n events; if every student in the queue was served, then print EMPTY.

Sample Input

ENTER John 3.75 50
ENTER Mark 3.8 24
ENTER Shafaet 3.7 35
ENTER Samiha 3.85 36
ENTER Ashley 3.9 42
ENTER Maria 3.6 46
ENTER Anik 3.95 49
ENTER Dan 3.95 50

Sample Output



Let’s call our queue Q.

n0: We add John to the empty queue.
Q0={(John, 3.75, 50)}

n1: We add Mark to the queue; Q1={(John, 3.75, 50),(Mark, 3.8, 24)

n2: We add Shafaet to the queue; Q2={(John, 3.75, 50),(Mark, 3.8, 24),(Shafaet, 3.7, 35)}

n3: Mark is served as he has the highest CGPA; P3={(John, 3.75, 50),(Shafaet, 3.7, 35)}

n4: John is served next as he has the highest CGPA; P4={(Shafaet, 3.7, 35)}

n5: We add Samiha to the queue; Q2={(Shafaet, 3.7, 35),(Samiha, 3.85, 36)}

n6: Samiha is served as she has the highest CGPA; P6={(Shafaet, 3.7, 35)}

n7 through n10, the next four students are added giving us:  Q10={(Shafaet, 3.7, 35),(Ashley, 3.9, 42),(Maria, 3.6, 46),(Anik, 3.95, 49),(Dan, 3.95, 50)}

n11: Anik is served because though both Anil and Dan have the highest CGPA but Anik comes first when sorted in alphabetic order; P11={(Dan, 3.95, 50),(Ashley, 3.9, 42),(Shafaet, 3.7, 35),(Maria, 3.6, 46)}

As all events are completed, we print names of each remaining students on a new line.



HackerRank: CodeWhiz.java March 2016: Maximum and Minimum


The locked code in your editor passes array A (of size N) and index i to the print method, whose try block attempts to print element A[i]; if i is Out-of-Range, an Array Index Out Of Bounds Exception is thrown.

Complete the code in your editor so that it prints the maximum and minimum elements in array A—regardless of whether or not an exception is thrown.

Input Format

The first line contains an integer, N, the number of elements in A.
The second line contains N space-separated integers describing A.
The third line contains an index, i, to be accessed.

Note: Input from stdin handled by the locked code in the editor.


  • 1N100
  • 1000Aj1000 where 1jN

Output Format

The try block will print the value accessed at A[i]; if an Exception is thrown, it will be printed by the locked code in your editor.
You must print the respective maximum and minimum values in array A as a single pair of space-separated integers on a new line—regardless of whether an exception is thrown.

Note: Observe that your max/min values may print on either the first or second line, depending on whether or not an Exception was thrown!

Sample Input 0

-12 0 1 -899 23 45 96 10 75 23 0 33

Sample Output 0

96 -899

Sample Input 1

4 908 -05 445 -208 325 -2 -718 863 400

Sample Output 1

908 -718


Sample 0:
N=12, i=100, maximum(A)=96, and minimum(A)=899
A‘s indices range from 0 to 11, so attempting to access index 100 throws an Exception. The maximum and minimum values in the array are printed on a new line as a pair of space-separated integers. The program’s control flow then returns to main where the the Exception is caught and printed on a new line.

Sample 1:
N=10, i=9, maximum(A)=908, and minimum(A)=718
A‘s indices range from 0 to 9, so an attempt to access index 9 will be successful and the value at A[9] (i.e.: 400) is printed on a new line. The program’s control flow then proceeds to print the maximum and minimum values in A as a pair of space-separated integers on a new line.


Unable to find valid certification path to requested target

Most of you must be familiar with the below exception message:

javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target

When trying to open an SSL connection to a host using Java.

Sample Code(source):

What this usually means is that the server is using a test certificate (possibly generated using keytool) rather than a certificate from a well known commercial Certification Authority such as Verisign or GoDaddy.

Web browsers display warning dialogs in this case, but since JSSE cannot assume an interactive user is present it just throws an exception by default.

To bypass this issue and be able to get the contents of a HTTPS url here is the steps:

First: use the below class code to install the required certificates(Source):

I was testing this on wikipedia.org, which is on https, thus facing the https issue.
You can modify the same as per requirement.

Next, set the following arguments while running JVM(source):

-Djavax.net.ssl.trustStore=<local path to certs>/jssecacerts

Next use the below code to get the contents(Source):

How to fix: Unsupported major.minor version xy.z error?

Occasionally in certain new environments using some libraries, we face the following Exception:

java.lang.UnsupportedClassVersionError: test_hello_world :
 Unsupported major.minor version 51.0
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClassCond(Unknown Source)

The problem here is about versions; some version of Java may be old or too new.

The version number shown describes the version of the JRE the class file is compatible with.

The reported major numbers are:

J2SE 8 = 52,
J2SE 7 = 51,
J2SE 6.0 = 50,
J2SE 5.0 = 49,
JDK 1.4 = 48,
JDK 1.3 = 47,
JDK 1.2 = 46,
JDK 1.1 = 45

(Source: wiki)

To fix the actual problem you should try to either run the Java code with a newer version of Java JRE or specify the target parameter to the Java compiler to instruct the compiler to create code compatible with earlier Java versions.

With newer versions of the Java compiler you are likely to get a warning about the bootstrap class path not being set. More information about this error is available in blog post New javac warning for setting an older source without bootclasspath.