Choosing a Language

TLDR: Start with cpp to get a good grasp on the low-level concepts. If you want to, switch to python to write code quicker and perform better in contests. Use java if you have a past background with the language.

Choosing the Right Language for DSA and LeetCode

Choosing the right programming language when starting out with data structures and algorithms (DSA) is crucial. The syntax, structure, and simplicity of a language can influence not just how quickly you can learn DSA concepts but also how efficiently you can solve problems under time constraints.

I believe that a language that lets you focus more on the actual logic and less on the boilerplate code can significantly enhance your problem-solving skills and improve your LeetCode journey.

Popular Languages for DSA

I will talk about the three major languages commonly used for DSA and LeetCode: cpp, python, and java.

I'll mostly share my personal perspective on the three languages but I have also done extensive research on each language. I have a decent bit of experience with cpp and python and have solved around 1300 problems in both the languages combined.

C++

Personally, I recommend starting with cpp. When I started my DSA + LeetCoding journey, I used cpp extensively and solved about 500-600 problems.

cpp is fast (irrelevant for LeetCode but yeah), and gives you a lot of control over memory. With cpp, you’ll need to understand how memory allocation, pointers, and data structures work, which can help avoid developing certain “bad habits” that can arise if you start with a language like python.

Once you’re comfortable with these low-level details and have a strong grasp of DSA concepts, switching to other languages becomes easier. In my opinion, python is a great language to switch to once you have grasped the low-level concepts.

cpp is also widely used in competitive programming, as evident from the high number of cpp submissions on LeetCode contest rankings. cpp is a great language to start if you really want to learn how things actually work.

Here's cpp code to calculate the sum of a list of numbers:

#include <iostream>
#include <vector>

int main() {
    std::vector<int> nums = {1, 2, 3, 4, 5};
    // Note that `accumulate` from C++ STL can be used to calculate the sum as well.
    // However, `sum()` from `python` is still much faster to write.
    int sum = 0;
    for (int num : nums) {
        sum += num;
    }
    std::cout << "Sum: " << sum << std::endl;
    return 0;
}

Python

These days, I primarily use python for DSA and LeetCoding. I have solved around 700 LeetCode problems in python as well. Its syntax is simple and highly readable, allowing you to focus on problem-solving without getting bogged down by complex syntax or memory management.

The simplicity makes it an excellent choice for interviews, as you can concentrate more on structuring your solution than on coding syntax. I believe that it's great for LeetCode contests as well since it allows you to write code quickly and efficiently. I have seen a great increase in my contest performance after switching to python.

While python may not be as performant as cpp, its ease of use and the vast libraries available make it ideal for interviews and many LeetCode problems. However, constant use of libraries while solving problems can lead to a lack of understanding of the underlying concepts.

python code to calculate the sum of a list of numbers:

# Note how python has no boilerplate code.
nums = [1, 2, 3, 4, 5]
sum_result = sum(nums)
print("Sum:", sum_result)

Java

Though I haven’t personally used java much for LeetCode or DSA, I’ve heard that it’s a fine choice for learning DSA as well. java provides a good balance between performance and abstraction, which can make it easier to understand object-oriented principles and work with built-in data structures.

If you already have a background in java, it can be a comfortable option for DSA. However, since I lack experience with java, I can’t provide as in-depth a perspective as I can for cpp and python.

import java.util.Arrays;

public class Main {
    public static void main(String[] args) {
        int[] nums = {1, 2, 3, 4, 5};
        int sum = Arrays.stream(nums).sum();
        System.out.println("Sum: " + sum);
    }
}

In summary, I recommend starting with cpp for a strong foundation, then switching to python as you gain proficiency and want to focus more on problem-solving rather than language specifics. Choose what works best for you, but remember that the language is ultimately just a tool; the goal is to learn DSA concepts deeply.