Algorithm Drill Linear Search

Summary

In computer science, there are different ways to search through collections of data. Understanding the various algorithms and patterns for searching and sorting data sets is an essential part of computer science.

While modern programming languages such as Python abstract many of the lower-level functions of programming by providing us with function like index()(Javascript equivalent method indexOf()), it is important to know what is going on underneath the hood. Employers look for people who understand how to put a car together, not someone who knows how to drive. Aside from being important to your knowledge of theory, the searching and sorting algorithms you use will have a significant impact on your program's performance (how long it takes to execute and how much memory it uses). We'll be talking about Big O notation soon.

One of the most basic searching algorithms is the linear search. In this challenge, you will build a linear_search function using very basic programming constructs.

Linear search (also called sequential search) is an algorithm for finding a particular value in a list by checking every one of its elements, one at a time and in sequence, until the desired one is found. Source: Wikipedia

Source: Practical Programming

Step 1 : Basic linear search

Write a function linear_search that takes two arguments: the object (i.e., string or number) you are searching for, and the array you're searching in.

Guidelines

• It should return an integer representing the index of the object in the array by going through each element in sequence and returning the index of the first instance of the object.
• If the object searched for does not exist in the array, it should return None(Python) or undefined(Javascript).

For the Python portion, you can't use any built-in list or Enumerable methods except for list(). You will have to use the keywords for, or while. There are some tests already in the spec file, but you should add more to prove that your code works correctly. Are there any edge cases you need to consider? Did you hit any bugs that should have had tests?

Step 2 : Global linear search

Write a new function global_linear_search that returns an array of all the indices for the object it searches for. In other words, if the object x is in more than one place in the array, global_linear_search will return an array containing the index of each occurrence of x.

Here's an example of what that might look like.

bananas_list = list('bananas')
# => ["b", "a", "n", "a", "n", "a", "s"]
global_linear_search("a", bananas_list)
# => [ 1, 3, 5 ]

We have added a few no tests for global_linear_search right now. Add some more to test your code.