Round 1 -

1. Add two linked lists and you cannot reverse a linked list and then add.
2. Detect cycle in undirected graph
3. Array of numbers given find minimum missing positive number from array. e.g 0,-1,1,4,5 minimum missing positive number from array is 2.
4. https://leetcode.com/problems/largest-rectangle-in-histogram/

The interviewer seemed to have crammed the answers and was not open to listening new approaches or ideas. In the span of 35 min 4 questions were asked and for the first question working code was expected.