Becoming better with vim

These are the things that I learn while on my vim journey

Here is good list of articles that you should read, to start with this is an excellent cheat sheet for vim

A Introductory cheatsheet, do this before going to another

http://www.viemu.com/a_vi_vim_graphical_cheat_sheet_tutorial.html

Then these articles are helpful

Moolenar : Good Vim Habits

ctags, is a very good tool for navigating through big projects.

Here is another very good blog about learning vim
http://yannesposito.com/Scratch/en/blog/Learn-Vim-Progressively/

definitely do the above before moving on.

Next steps after learning these shortcuts is having a good .vimrc file, which is basically a configuration file for your vim( stored in the HOME directory). You can search for popular .vimrc on the net. I'll list a few that I find good

Plugins , now as suggested by a friend I started using vundle , which is a vim plugin manager.

• NERDTree is a must to have when working on code base. 
• Cscope is also a needed when working with large code base, refer to the link for setting up Cscope with vim. Also, do the following for automatic cscope.out detection http://vim.wikia.com/wiki/Autoloading_Cscope_Database 
• Along with NERDTree , you need to learn how to use split screens in vim which is very usefull when working with multiple files. https://www.cs.oberlin.edu/~kuperman/help/vim/windows.html

 

Minimum No. of Jumps

Given an array of non-negative integers, you are initially positioned at the first index of the array.
Each element in the array represents your maximum jump length at that position.
Your goal is to reach the last index in the minimum number of jumps.
Example :
Given array A = [2,3,1,1,4]
The minimum number of jumps to reach the last index is 2. (Jump 1 step from index 0 to 1, then 3 steps to the last index.)
If it is not possible to reach the end index, return -1.

 Follow this link to read a O(n^2) solution GeeksforGeeks: Minimum number of jumps

Read my O(n) solution below

Maximum Product Subarray

One of the standard dp problems, the approach given below is similar to kadane algorithm for maximum subarray sum problem. The code given below fails when negative output is the max possible. For example the input

Input : -4

Comments are welcome.

Preparing for the Coding Interview

Here are a few things that I did while preparing for my placements and a few things that I think I should have done.

This post is written with the plan that you have max of 6 months left before the D-Day, for people in the their 2nd or 3rd years there is a variety of things that would further enhance their chances of being placed.

<-------------------------- 6 Months -------------------------------->
www.geeksforgeeks.org    This is a very big repository of coding interview questions and preparations material. Usually one would require about 6 months to go through the whole material.

<--------------------------- 4 - 5 Months --------------------->

After having read the standard algorithms and Data Structures, its time to gain some coding experience

www.interviewbit.com This site is very good for coders with not much experience, you will have revision of concepts and get practice at the same time. It provides a gaming level sort of UI to make it interesting, which a growing community.

www.leetcode.com This is another site is popular among coders for interview preparation, but many questions between interviewbit and this overlaps so do one of them. InterviewBit has more structure and organization for preparation.

<------------------------------1-2 Months ---------------------------->

Hopefully above level of preparation would be sufficient for clearing hte coding rounds and you are now shortlisted your dream companies. So brush up the topics on your resume and prepare for the specific domains like Networks, OS .

Some important topics to prepare for :
1. Linked List
2. Stacks and Queues
3. Dynamic Programming ( geeksforgeeks has an extensive collection)
4. Greedy
5. Backtracking 
6. Graph Theory ( dfs and bfs will do for most except google,fb ) 


Comments and suggestions are welcome . 

Getting started with Python API for Facebook

Install the repository with

sudo pip install facebook-sdk

Here is a sample program to print the name of your friends 

To get the oauth_access_token follow this link Graph API Explorer

See the following the snippet for printing posts with some specific substring in them. This way we can complete the hack of posting multiple comments on similar posts

I found another python libray, which seems more easier to use than this one. visit that Facepy

SPOJ PRATA

The problem : www.spoj.com/problems/PRATA/

Solution: There are many solutions one can use binary search which is straight forward if you understand the concept of binary search . Use the link to find a binary search based implementation

http://spoj-solutions.blogspot.in/2014/10/prata-roti-prata.html

I used a min-heap based solution. The algorithm is to find the the cook who will next become free and assign him a prata, as simple as that.

My solution is O(p*L) which got accepted. You can find the code through following link
https://github.com/kanirudh/spoj/blob/master/prata.cpp

Comment below in case of queries.

A list of algorithms for Competitive Programming

Solving problems on SPOJ, I realised I used to forget the algorithms which I had previously used. For this fallacy of mine I am listing the algorithms and the corresponding SPOJ problems. There may be better resources on net similar to this but this is my effort. You can also find solutions to these problems on my github page http://www.github.com/kanirudh/SPOJ/

1. Sorting:
     Using the library function for sorting usually does the trick. You need to know how to define a comparator function for sorting user-defined structure arrays.
   
     http://www.spoj.com/problems/DOTAA/

2. String Algorithms
 
     Patten Matching
     a) KMP Algorithm
     http://www.spoj.com/problems/NHAY/
     b) Rabin Karp 

3. Dynamic Programming Algorithms
   
     a) 0/1 Knapsack
     http://www.spoj.com/problems/LKS/
   
     b) Longest Increasing Subsequence
     http://www.spoj.com/problems/XMEN/

     c) Longest Common Subsequence
     http://www.spoj.com/problems/LCS/
     http://www.spoj.com/problems/TRIP/

4. Divide And Conquer
     a) Closest Pair of Points
     http://www.spoj.com/problems/CLOPPAIR/

     b) Binary Search
     http://www.spoj.com/problems/PIE/
     http://www.spoj.com/problems/EKO/
     http://www.spoj.com/problems/OPCPIZZA/
 

5. Graph Algorithms
    ( DFS, BFS, Djisktra, Floyd-Warshall, Bellman-Ford, kruskal)
    http://www.spoj.com/problems/PARADOX/

6. Maths
    Gaussian Elimination
    http://www.spoj.com/problems/XMAX/