Bonetrousle - HackerRank world code sprint #6 - Practice 1

August 28, 2016

Problem statement:
https://www.hackerrank.com/contests/world-codesprint-6/challenges/bonetrousle

Julia was naive on planning, management of time, tried to solve this algorithm, without any hesitation. She tried to score any point above 0, found the idea to write code using stack, but with additional 2+ hours to review code, stayed overnight, from 12:00am - 2:45am, a brute force solution. She did not make any (over 10 test cases: 5+ wrong answer, 4+ time out). So, she wrote down the experience to celebrate her weekend, over middle night struggling with an algorithm.

Share some statistics of world code sprint #6 workout:
Current Rank: 1112 - score 100/ 380 (score first 4 algorithms full score)

First practice:

Use stack, brute force, each box has two choice, join or skip. She tried to implement the brute force solution first, and then, she recalled the previous work on algorithm Leetcode: phone number:

https://gist.github.com/jianminchen/872bf70039fa8c61ff208b34a591c8ec

Only pass the test cases provided in the problem description.

https://gist.github.com/jianminchen/e3fc7d23a62274b207ddc41a06030cd4

Statistics:
score 0 out of 50 points.

Brute facts:
A brute force solution does not score any points - even pass the basic test case - test case 1.

Actionable Item:

Write a blog about this algorithm, document the importance of time complexity analysis; how to plan to spend time to work on a solution.

http://juliachencoding.blogspot.ca/2016/08/bonetrousle-hackerrank-world-code_75.html

Algorithm: Count the number of palindromes in a string

Count the number of palindromes in  a string

January 28, 2016

    Write down ideas:
    1. First of all, do not count duplicate.
    2. Brute force solution:
 any substring of O(N^2) substrings to see if it is a palindrome;
 Add the substring of palindrome to a hashset if it is not in the hashset.
  And return the length of hashset
    3. Use recursive solution - using subproblem to solve. Cannot filter out duplicate - not good
    4. Better solution - use center point of string - 2n + 1, and then, go over each one, add all palindromes substring.

  Requirement: write a C# code in 10 minutes for the solution, using brute force one.

  https://github.com/jianminchen/AlgorithmsPractice/blob/master/NumberOfDistinctPalindromes.cs

Leetcode 5: Longest substring palindrome

January 13, 2016

Read the blog: 

http://blog.csdn.net/linhuanmars/article/details/20888595
http://blog.csdn.net/linhuanmars/article/details/22777711

Please read 5-6 solution about this leetcode question, and then, collect all the wisdom. Try to have nice memory about the solution, some fun experience; therefore, it will be a quick and fun time to solve the similar problems in the future.

Do not rush to finish more leetcode questions. Try to focus on simple problems.

There are 5 solutions discussed in the following blog, most important is to give overview of 5 analysis, what is brute force solution - time, space complexity.

One way to make review more fun is to read more than 10 - 20 solutions, and know all the ideas out there, and then, write some code; Reading is most important to help understand algorithms, through a simple problem, common interview question.

http://articles.leetcode.com/2011/11/longest-palindromic-substring-part-i.html

4 solutions in the above blog

one optimal solution - linear time solution in the following blog:
http://articles.leetcode.com/2011/11/longest-palindromic-substring-part-ii.html

This blog is in Chinese. Excellent! Try to summary a few tips to come out linear time optimal solution! Do something to get more involved.

http://www.felix021.com/blog/read.php?2040

spent 10 minutes to read the article, enjoyed the reading; a good article with very well explained brute force solution, how good is to work on linear solution in time complexity. 
https://www.akalin.com/longest-palindrome-linear-time

Read the blog:
http://www.acmerblog.com/leetcode-longest-palindromic-substring-5356.html

6th solution, a suffix tree solution:
http://www.allisons.org/ll/AlgDS/Tree/Suffix/

First blog about this leetcode question:

http://juliachencoding.blogspot.ca/2015/06/leetcode-longest-palndromic-substring.html

Another palindrome algorithm #9
https://github.com/jianminchen/Leetcode_C-/blob/master/9palindromeNumber.cs

Leetcode 5: longest palindromic substring

Problem statement:

Given a string S, find the longest palindromic substring in S.

June 15, 2015

Websites to read:

http://www.programcreek.com/2013/12/leetcode-solution-of-longest-palindromic-substring-java/

https://yanbxice.wordpress.com/2015/05/31/leetcode-longest-palindromic-substring/

题目分析很透彻, 很有帮助! 

https://leetcodenotes.wordpress.com/tag/palindrome/

C# code on github:

https://github.com/jianminchen/palindrome/blob/master/Program.cs

https://github.com/jianminchen/Leetcode_C-/blob/master/5LongestPalindromicSubstring.cs
https://github.com/jianminchen/Leetcode_C-/blob/master/5LongestPalindromic_B.cs

January 2, 2016

Review the algorithm. 

Leetcode question: 5. Longest Palindromic Substring

https://github.com/jianminchen/Leetcode_C-/blob/master/5LongestPalindromicSubstring.cs

January 13, 2016

Read the blog: 

http://blog.csdn.net/linhuanmars/article/details/20888595
http://blog.csdn.net/linhuanmars/article/details/22777711

Please read 5-6 solution about this leetcode question, and then, collect all the wisdom. Try to have nice memory about the solution, some fun experience; therefore, it will be a quick and fun time to solve the similar problems in the future.

Do not rush to finish more leetcode questions. Try to focus on simple problems.

There are 5 solutions discussed in the following blog, most important is to give overview of 5 analysis, what is brute force solution - time, space complexity.

One way to make review more fun is to read more than 10 - 20 solutions, and know all the ideas out there, and then, write some code; Reading is most important to help understand algorithms, through a simple problem, common interview question.

http://articles.leetcode.com/2011/11/longest-palindromic-substring-part-i.html

4 solutions in the above blog

one optimal solution - linear time solution in the following blog:
http://articles.leetcode.com/2011/11/longest-palindromic-substring-part-ii.html

This blog is in Chinese. Excellent! Try to summary a few tips to come out linear time optimal solution! Do something to get more involved.

http://www.felix021.com/blog/read.php?2040

spent 10 minutes to read the article,
https://www.akalin.com/longest-palindrome-linear-time

Read the blog:
http://www.acmerblog.com/leetcode-longest-palindromic-substring-5356.html

6th solution, a suffix tree solution:
http://www.allisons.org/ll/AlgDS/Tree/Suffix/

January 7, 2017
3 code reviews:
Longest palindrome string - best review - no raw loop.