Miss problem 159 Longest Substring with At Most Two Distinct Character. 

## 🐛 Bug Report

Miss problem 159.

## To Reproduce

select the search button and input 159 or related keywords 

## Expected behavior

159 problem pops up!

## Your Environment

- *os*:
- *extension settings*:
- *nodejs version*:
- *vscode version*:
- *extension version*:
