Code review: Leetcode 10: regular expression matching

Dec. 26, 2017

Introduction

It is another mock interview 12:00 PM. I had chance to help the peer solve Leetcode 10: regular expression matching. I did not expect that the peer can solve the problem almost perfectly. I was so surprised to learn from the peer how he wrote an elegant recursive function using while loop.

Code to study

Here is the peer's C# code. I like the implementation.

The above code failed last test case, "abaa" and pattern string "a.*a*". It should return true.

Here is the code to fix the above bug. The code passes all test cases on mock interview platform. But it failed on Leetcode 10 online judge.

Index out of range error, Line 28: System.IndexOutOfRangeException: Index was outside the bounds of the array. Last executed input: "ab" and ".*c"

Line 28: If(text[tIndex] != pattern[pIndex])

Actionable Item

After spending over 30 minutes to debug the issues using Leetcode 10 online judge, I learned that the recursive solution has a lot of issues. Later I will revisit the solution and give more objective comment on this solution.