This is about bug in binary search implementation in java which is detected 9 years later

JVM internals:

https://youtu.be/ZBJ0u9MaKtM?si=r-Ba6zxkywIMpOl7

Recently had an interview for Junior Java Engineer role at Vention Teams. Below you can find sample questions that i was asked during interview:

https://telegra.ph/Vention--Interview--Junior-Java-Engineer-07-31

Hi, recently had a Project Interview at Epam Systems, below you can find the questions:

https://telegra.ph/Java--Project-Interview--Epam-Systems-09-11

Spent more then an hour to solve this problem and finally solved it 🎯:)

java  
/*  
// Definition for a Node.  
class Node {  
    public int val;  
    public List<Node> neighbors;  
    public Node() {  
        val = 0;  
        neighbors = new ArrayList<Node>();  
    }  
    public Node(int _val) {  
        val = _val;  
        neighbors = new ArrayList<Node>();  
    }  
    public Node(int _val, ArrayList<Node> _neighbors) {  
        val = _val;  
        neighbors = _neighbors;  
    }  
}  
*/  
  
class Solution {  
    public Node cloneGraph(Node node) {  
         
        if (node == null) {  
            return node;  
        }  
  
        Set<Integer> visited = new HashSet<>();  
        Map<Integer, Node> clones = new HashMap<>();  
        Queue<Node> q = new LinkedList<>();  
        q.add(node);  
  
        while (!q.isEmpty()) {  
  
            Node currNode = q.poll();  
            int currVal = currNode.val;  
  
            if (!visited.contains(currVal)) {  
  
                Node nodeClone = clones.getOrDefault(currVal, new Node(currVal));  
                clones.put(currVal, nodeClone);  
  
                for (Node child : currNode.neighbors) {  
                    if (child == null) continue;  
                    Node childClone = clones.getOrDefault(child.val, new Node(child.val));  
                    clones.put(child.val, childClone);  
                    nodeClone.neighbors.add(childClone);  
                    q.add(child);  
                }  
                  
                visited.add(currVal);  
            }  
        }  
  
        return clones.isEmpty() ? node : clones.get(1);  
    }  
}  
 

#leetcode

Excited to share that I passed AWS Certified Solutions Architect – Associate exam
Link: https://www.credly.com/badges/2f8bb511-341a-4414-bc09-8b7a79d5e07b/public_url

Solved an interesting leetcode problem today after so many try:

class Solution {

    Map<Character, Integer> freq = new HashMap<>();
    Map<Character, Integer> count = new HashMap<>();

    public int leastInterval(char[] tasks, int n) {

        for (char task : tasks) {
            freq.put(task, 0);
            count.put(task, count.getOrDefault(task, 0) + 1);
        }

        PriorityQueue<Character> q = new PriorityQueue<>(new CustomOrder());
        Set<Character> seen = new HashSet<>();

        for (char task : tasks) {
            if (seen.contains(task)) {
                continue;
            }
            q.add(task);
            seen.add(task);
        }


        int intervals = 0;
        while (!q.isEmpty()) {

            boolean hasTask = false;
            Queue<Character> tmpQ = new LinkedList<>();
            int size = q.size();
            for (int i = 0; i < size; i++) {
                char task = q.poll();

                if (freq.get(task) == 0) {
                    intervals += 1;
                    count.put(task, count.get(task) - 1);
                    if (count.get(task) > 0) {
                        tmpQ.add(task);
                    }
                    decreaseFreq();
                    freq.put(task, n);
                    hasTask = true;
                    break;
                }else {
                    tmpQ.add(task);
                }
            }

            if (!hasTask) {
                // cpu idle
                decreaseFreq();
                intervals += 1;
            }
            q.addAll(tmpQ);
        }

        return intervals;
    }

    private void decreaseFreq() {
        for (Map.Entry<Character, Integer> entry : freq.entrySet()) {
            char key = entry.getKey();
            int occur = entry.getValue();

            if (occur > 0) {
                freq.put(key, occur - 1);
            }
        }
    }

    class CustomOrder implements Comparator<Character> {

        @Override
        public int compare(Character t1, Character t2) {
            if (count.get(t1) > count.get(t2)) {
                return -1;
            }else if (count.get(t2) > count.get(t1)) {
                return 1;
            }else {
                return 0;
            }
        }

    }
}

Problem Link: https://leetcode.com/problems/task-scheduler/

What will be the output of this program:

class Person {
  Person() {
    System.out.print("CP ");
  }

  static {
    System.out.print("SP ");
  }
}

class Manager extends Person {
  Manager() {
    System.out.print("CT ");
  }

  {
    System.out.print("IT ");
  }
}

class Program {
  public static void main(String[] args) {
    Person p1 = new Manager();
  }
}

Explanation:

Option C is the correct answer.
The static contents are executed when the class is loaded so before the constructors are executed, so the SP will be printed first.  Then the constructor of Person will print CP. Then the Manager class instance code block will print IT before Constructor prints CT.  So, the output is SP CP IT CT. Therefore, option C is correct.
Static content will print only once. So, option D is incorrect.
Other outputs are incorrect as explained above.
The Code compiles fine so, option E is incorrect.

REFERENCE: http://docs.oracle.com/javase/tutorial/java/IandI/super.html http://docs.oracle.com/javase/tutorial/java/IandI/super.html

What will be the output of this program:

import java.util.List;

public class MJC {

    public static void main(String args[]) {

        int factor = 2;
        List<Integer> nums = List.of(1, 2, 3, 4, 5);
        nums.stream()
                .map(num -> num * factor)
                .forEach(System.out::print);
        factor += 1;
    }
}

Explanation:

Option D is correct.
Lambda expression can only access local variables and parameters of the enclosing block that are final or effectively final. In above code factor does not meet this requirement and compilation fails.

References:
https://docs.oracle.com/javase/tutorial/java/javaOO/lambdaexpressions.html#syntax

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