sagivo / algorithms

algorithms playground for common questions

Algorithms

Algorithms playground for common questions solved in ruby syntax.
In case you want to prepare yourself for a job interview - try to solve it yourself first, then have a look here.

Why?

I interviewed with Google, Facebook, LinkedIn, Twitter and others. I also interviewed others myself. Sometimes it looks like they all ask you the same "out of the box" questions that don't really check knowledge but memorization of the same tricks. This is my way of saying - change your interview style. There are lots of smart people out there, this is not the best way to find them.

Problems

problem	solution
Unique binary search trees	click
House Robber	click
Decode Ways	click
Coin change	click
Decode Strings	click
Wiggle Subsequence	click
Binary Tree Side View	click
Unix path	click
Array Product	click
Top K Frequent Elements	click
Sum 4 arrays	click
Reverse Linked List	click
Reverse String In-place	click
Nested List Weight Sum II	click
Symmetric Tree	click
Dijkstra's shortest path between two nodes	click
Kruskal's minimum spanning tree algorithm	click
Find the square root of a number	click
Add two binary numbers	click
Binary search	click
Longest increasing subsequence	click
Find all permutations of array	click
Finding all combinations of well-formed brackets	click
Finding the powerset of a set	click
Game of life	click
Print all combinations of set joining	click
count and say	click
Telephone number to words	click
Maximum contiguous subarray	click
Max Stack	click
Find the smallest biggest number that has the same digits	click
Find the minimum insertions needed to make a word palindrome	click
String matching - Knuth Morris Pratt algorithm KMP	click
Balanced Parentheses	click
Quicksort algorithm	click
Mergesort algorithm	click
Max Stocks Profit	click
Countingsort algorithm	click
Shellsort algorithm	click
Knapsack problem	click, click
Move Zeroes	click
Longest common subsequence problem	click , click
Monty Hall Problem	click
Eucliden and Extended Eucliden algorithm	click
Suggest index of a number in an array	click
Range minimum query sparse table algorithm	click
Insertion Sort	click
Towers of Hanoi using Stack	click
Tarjan's strongly connected components finder	click

How?

Simply run ruby some_file.rb to execute the algorithm. At the bottom of each file there are some test samples.
example: ruby brackets_combinations.rb will print:
["((()))", "(()())", "(())()", "()(())", "()()()"].

Contribute

Did you find a bug? any way to do it better? please feel free to pull-request it :)