• Practice algorithmic problem solving

Given a string s, find the length of the longest substring without repeating characters.

Input: s = "abcabcbb"
Output: 3

Explanation: The answer is "abc", with the length of 3.

Input: s = "pwwkew"
Output: 3

Explanation: The answer is "wke", with the length of 3. Notice that the answer must be a substring, "pwke" is a subsequence and not a substring.

Input: s = ""
Output: 0

1. Rewrite the problem in your own words
2. Validate that you understand the problem
3. Write your own test cases
4. Pseudocode
5. Code!

And remember, don't run our tests until you've passed your own!

BONUS: For students who did not achieve O(n) on longest substring, refactor solution until achieved.

1. cd into the ruby folder
2. ruby <filename>.rb

1. cd into the javascript folder
2. node <filename>.js

1. cd into the ruby folder
2. bundle install
3. rspec

1. cd into the javascript folder
2. npm i
3. npm test