Round 1 had 2 sections, One was a coding round having 2 problems.
1: Given a list of Students and Subjects along with credits of each, a student can select only those subjects whose credits are less than equal to his/her credits.
Return the number of pairs of students and subjects.
So there can be 7 pairs as The Student having 5 credits can select all the subjects and the student having credits 3 can select subjects with credits 1,2,3.
Easy Binary search and sort question.
2. Find LCA of a binary tree.
Article Link Problem Link
Both questions were fairly easy but required to be done in 30 minutes.
Round2 was a technical round and was fairly easy. The interviewer was very friendly and started the discussion with my projects and internships.
Then he asked me a few SQL queries related to self-join and find Manager and employee in a given table.
Few basic C/C++ questions like What is dangling pointer, Post increment operator, Static functions.
Then a programming question on Sieve. Then few easy puzzles like 3 bulbs and 3 switches puzzle and a bee traveling between two trains. All available on GeeksForGeeks.
Round 3 was semi-technical. It started off with a small case study which was very interesting and based on Cricket World Cup and How American Express can tie-up with Hilton Hotel. Then a question on trie because it was mentioned in my resume and it ended up really well.
Round 4 HR:
Very General Questions on Why American Express, strengths and Weakness, Plans of Future Studies, and Which team would I select if given a chance.