You are given a list of call stacks, which represents the call stack at a particular instance of time starting from 0 ms, say at every ms. You need to create a call graph from this data, which is a hierarchical structure and also provide the time in ms, that each call in the hierarchy took. After I struggled a bit, the question was further simplified where I had to find the number of times a particular method is called and also provide a parent-child hierarchy between the calls. So basically, the input was a list of stacks and the output was a tree graph with count of each method.
