Paytm Interview Experience (Experienced)

Round 1:

Online Coding round

1. A document contains dates in dd-MM-YYYY formats from the beginning of time i.e 00-00-0000 along with other texts. You have to find the number of distinct years.
2. An array is special if it contains special elements. A special element is an element which can be represented by the sum of two numbers where one number is reverse of other. Like Array is {22, 121} . Here 22 = 11 + 11 and 121 = 92 + 29. Hence both elements are special. The input array is an array of strings. Output number of special elements in the array.

//Write Java code here

//Added By Naga Praveen Kumar
public class SpecialNumber {
    public static void main(String[] args) {
        int[] arr = {22,121};
        printspecialElements(arr);
    }


    public static void printspecialElements(int[] arr){

        for(int i=0;i<arr.length;i++){
            if(arr[i]%11 == 0){
                System.out.println(arr[i]);
            }
        }

    }

}

Round 2:

F2F

1. About my project in last company
2. Transaction Isolation levels
3. Connection pools in java
4. How to maintain idempotency in case of failure of REST API.
5. Give an example where you used transactions.
6. Aerospike and Redis differences and advantages (Written in my resume).
7. The average response time of Redis.
8. Mysql locking

Round 3:

F2F

1. Introduction and projects
2. Find two elements in BST who sum is equal to a given number.
3. Find oldest non-repeating character in the stream of characters.
4. Was asked to implement the above question in case of multi-threaded environment.
5. Singleton class and use cases and creation techniques.
6. Garbage collection working in java.

Round 4:

F2F

1. In-depth discussion of my work in last company.
2. Design twitter along with use cases.

Thank you GeeksForGeeks for helping me with my preparations. 🙂