The problem was to create a heap, where you could add elements and remove the top element, with the contraints that the top-most element had to always be less than the top most element in the left child tree, and less than the top most element in the right child tree, and that the left child tree had to have as many or one more element than the right child tree. Furthermore, there was a "min" function (returns the value at the top of the tree) and an empty function (returns an empty tree). The interview started using a collabedit software tool where the interviewer and I could rapidly write and exchange code. Having not been comfortable with the syntax and structure of OCaml, I noted that the person who set up the interview told me it wasn't a requirement, but I was told to carry on in OCaml. With all that said, my preoccupation with not knowing the syntax led me to make simple functional mistakes, the interview took longer than expected, and after a week of waiting for a response, I was rejected. The code I'm attaching is a combination of what we did through the interview, and what I finished off in my own time (my_merge, create_tree)