DEV Community: Gilfoyle

Best Free Resources to Practice Leetcode Effectively!

Gilfoyle — Tue, 13 Sep 2022 08:21:46 +0000

If you have been in the market and looking for a job, I am pretty sure you have heard of Leetcode,it's a website to practice data structures and algorithms. In this post I am going to share with you the best resources to practice Leetcode effectively.

List of Resources

Neetcode
This website has a free list of practice questions, it also has paid courses for people who are interested.
Sean Prashad Leetcode Patterns List
This website has a list of practice questions with the the most common patterns on Leetcode (I highly recommend learning the most common patterns on Leetcode).
Blind 75
This is a list of questions that teaches you core concepts and techniques for each category/type of problems.

Here you have the best free three resources to practice Leetcode effectively. If you want more content like that please consider following me on Twitter. Thanks for reading.

How to Find The Frequency of Characters in a String or Array

Gilfoyle — Mon, 12 Sep 2022 05:46:58 +0000

In this post I am going to tech you how to find the frequency of characters in a string or array. This is a common question in interviews. I will be explaining the code in Java and JavaScript.

Question prompt

Write a function, charFrequency, that takes in a string/array as an argument. The function should return the the frequency of each character in the string/array then return the answer as map or dictionary.

You can assume that the input string is non-empty.

example_00

mostFrequentChar('david'); -> Map={ 'd' => 2, 'a' => 1, 'v' => 1, 'i' => 1 }

example_01:

mostFrequentChar('bookeeper'); // -> Map= { 'b' => 1, 'o' => 2, 'k' => 1, 'e' => 3, 'p' => 1, 'r' => 1 }

JavaScript Solution

const charFrequency = (str) => {

  //create a map to save the characters and save the frequency of each character
  const frequencyMap = new Map();
  //go through each character in the string 'str' 
  for(let char of str)
    {
      //check if our map doesn't contain the current character we are going through
      if(!frequencyMap.has(char))
        {
          //if our map doesn't contain the character we add it and assign the frequency to 1      
          frequencyMap.set(char,1);
        }
      //check if our map does contain the current character 
      else
        {
          // if our map contains the current character we are going to add 1 to the character frequency value
          //example, if we had 'd' => 1, we are going to get the value of 'd' and add 1 to it
          // so 'd' frequency value beacomes 2 
          frequencyMap.set(char,frequencyMap.get(char)+1);
        }
    }

  //return the frequencyMap we created 
  return frequencyMap;
}

Java Solution

public String frequencySort(String str) {
  //create a map to save the characters and save the frequency of each character
  HashMap<Character,Integer> frequencyMap = new HashMap();
  //go through the string 'str' 
  for(char ch : str.toCharArray())
    {
      //check if our map contains the current character we are going through
      if(!frequencyMap.containsKey(ch))
        {
          //if our map doesn't contain the character we add it and assign the frequency to 1      
          frequencyMap.put(ch,1);
        }
      //check if our map does contain the current character 
      else
        {
          // if our map contains the current character we are going to add 1 to the character frequency value
          //example, if we had 'd' => 1, we are going to get the value of 'd' and add 1 to it
          // so 'd' frequency value beacomes 2 
          frequencyMap.put(ch,frequencyMap.get(ch)+1);
        }
    }

  //return the frequencyMap we created 
  return frequencyMap;
}

This is how we get the frequency of characters in a string or array. If you have any questions, please let me know in the comments section. Also consider following me on Twitter if you want more content like this.

How I was able to make $150,000 fresh out of college

Gilfoyle — Sun, 11 Sep 2022 21:33:29 +0000

In this post I am going to be talking about how I was able to make fix figures fresh out of college as a Software Engineer. Before getting into that though, I want to give you a quick background about my eduction.

Background

I went to a state university in The San Francisco Bay Area for a degree in Computer Science. I wasn't an A student at all, I was barely making it.

The Path to $150,000

During my 3rd year in college I started practicing for interviews to get an internship (it's important to get an internship during college.) After interviewing for 3 months, I was able to land an internship at a non-tech company. The pay wasn't that great ($20/hr), but I wanted something to add on my resume to be able to get another internship or a full-time job. The internship lasted 3 months. After that I continued interviewing for other internships and I was able to get another internship at a tech startup this time. By the time I finished this internship I was in my last semester in college, so I started applying for full time jobs. My job hunt for a full time job lasted for the whole semester. I was able to get around 11 interviews, I failed 8 of them and got 3 offers. I picked the best one based on the salary and the company name.

The Most Important Leetcode Patterns

Gilfoyle — Sun, 11 Sep 2022 03:39:10 +0000

If you have been looking for a job in tech, I am pretty sure you have heard of Leetcode, it's a website that helps you learn and practice Data Structures and Algorithms to pass the coding interview. so without farther due let's talk about the most important patterns to solve any Leetcode style questions.

Sliding Window
Two Pointers
Fast & Slow pointers (LinkedList)
Tree Breadth First Search aka BFS
Tree Depth First Search aka DFS
Hashing (using HashTable or Map)
Dynamic Programming

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