1. Given array = [1,1,1,1,6,6,6,6,3,3,4,4]

• How to present mentioned array efficiently in memory.
• Compute dot product of two such vectors without expanding the input.

Similar to https://leetcode.com/problems/product-of-two-run-length-encoded-arrays/
Output should be int instead of encoded vector.

I took 20 mins for above question.

2. Remove duplicates from string, after removal remaining characters will slide in.
   eg: "abbba" -> "aa" -> ""
   "ab" -> ""

   Solution: Was able to came up with below approach only.

   `public static String compress(String input){

   Stack stack = new Stack<>();
   boolean doDelete = false;
   char previous = 'a';
   for(char c : input.toCharArray()){

   if(previous != c && doDelete){
   stack.pop();
   doDelete = false;
   }

   if(!stack.isEmpty() && stack.peek() == c){
   doDelete = true;
   continue;
   }

   stack.push(c);
   previous = c;
   }

   if(doDelete)
   stack.pop();

   StringBuilder sb = new StringBuilder();
   for(char c : stack)
   sb.append(c);

   return sb.toString();
   }`

Key points

1. Keep a short and interesting introduction.
2. You need to get an agreement on approach, complexity before starting code under 5 mins.
3. Try to practice as much as possible and write code in 5 mins.
4. Dry run on inputs and edge cases in 5 mins.
5. Its ok to take a pause between questions to calm yourself, take a deep breath, sip of water and then focus.
6. If stuck, request for hints politely. Its ok and better than pin drop silence.
7. Show gratitude towards end :)

Time management - 5 (Intro) + { 2 * {5 (question + approach) + 5 (code) + 5 (dry run + edge cases)}} + 5 (QnA) ~ 40 mins.
Ofcourse 5 min is buffer as things might not go as planned.

Got confirmation from recruiter within a day that I can proceed to onsite.