Testdome Java Questions And Answers Now

TestDome scores range 0–100% .

Most companies set a passing threshold at 75% . If you score below, they often do not proceed to the next interview round.

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Question:
Write a function that merges two strings alternately, starting with the first string. If one string is longer, append the remaining characters.

Example:
"abc", "123" → "a1b2c3"
"ab", "1234" → "a1b234" testdome java questions and answers

Solution:

public class StringMerge 
    public static String merge(String s1, String s2)  i < s2.length()) 
            if (i < s1.length()) result.append(s1.charAt(i));
            if (i < s2.length()) result.append(s2.charAt(i));
            i++;
return result.toString();

Why it works:

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Before your actual exam, write code for these variations: TestDome scores range 0–100%

A. Palindrome with Mixed Cases

// Returns true if string is palindrome, ignoring case and non-alphanumeric
public static boolean isPalindrome(String s) 
    // Write solution using two pointers

B. User Roles (Enum + Set)

// Given a list of permissions (READ, WRITE, DELETE), return true if user can perform action
enum Permission  READ, WRITE, DELETE 
class User 
    Set<Permission> permissions;
    public boolean can(Permission p)  ...

C. Cache with LRU (Hard)

// Implement an LRU cache with get(key) and put(key, value) methods
// Use LinkedHashMap with accessOrder=true

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import java.util.ArrayDeque;
import java.util.Deque;
public class TrainComposition 
private Deque<Integer> deque = new ArrayDeque<>();
public void attachWagonFromLeft(int wagonId) 
    deque.addFirst(wagonId);
public void attachWagonFromRight(int wagonId) 
    deque.addLast(wagonId);
public int detachWagonFromLeft() 
    if (deque.isEmpty()) return -1; // Required by grader
    return deque.removeFirst();
public int detachWagonFromRight() 
    if (deque.isEmpty()) return -1;
    return deque.removeLast();

Key insight: ArrayDeque offers O(1) insertion/removal at both ends. LinkedList would also work but uses more memory. Returning -1 on empty deque is specific to TestDome's hidden expectations.

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