Leetcode 315: Count of Smaller Numbers After Self

January 6, 2018

Introduction

It is the hard level algorithm and I am still working on the problem solving. Today after 4:00 PM mock interview, I asked the peer how to solve the algorithm. Since the peer is preparing Google onsite next month, I like to test how good he is in terms of algorithm analysis.

We had discussion around 10 - 15 minutes on the algorithm. We brainstorm the algorithm, since I worked on the algorithm more than 2 hours before, and he told me that this is the first time for him to work on the algorithm.

We discussed array, sorting, sorting to keep the index value, and then I talked about the preprocessing the data into a binary search tree. And then the peer told me to look into binary index tree, and then the discussion went on with understanding the binary index tree.