I made some syntax errors in this one. Be careful.

This was a greedy problem.
1. Sort the array of coins in decreasing order. Initialize result as empty.
2. Find the largest denomination that is smaller than current amount.
3. Add found denomination to result.
4. Subtract value of found denomination from amount.
5. If amount becomes 0, then print result.
6. Else repeat steps 3 and 4 for new value of V.

The recursive approach is to generate all possible sums from all the values of the array and to check which solution is the most optimal one. 
To generate sums we either include the i’th item in set 1 or don’t include, i.e., include in set 2.
More optimized solution is Dynamic Programming.

Solve string questions

1. Start from brute force approach by using another stack.
2. Optimise it with reducing push and pop operations.
3. Optimise it to O(1) space complexity.

1. I started with brute force approach using three loops.
2. I optimized it to two loops by using sorting and two pointer technique.

Tip 1 : Explain what deadlock is briefly.
Tip 2 : Be confident while answering.
Tip 3 : Explain its conditions in detail. Refer to youtube channel gate smashers for clarity of topic.

I used hash maps to solve the problems.
 

1. I started with brute force approach of sorting the array and then finding the kth smallest element. This was O(nlogn) approach.
2. Then I solved using heaps with an O(n) approach.

Used hare and tortoise method to solve this problem.