Competitive Coding tricks in Python

Competitive coding, also known as competitive programming or coding competitions, requires efficient and fast problem-solving skills. Here are some Python tricks and techniques that can help you excel in competitive coding:

Read Input Efficiently:

• Use input() for reading input from standard input (stdin) and print() for output to standard output (stdout).
• Use the split() method to split space-separated input values into a list of strings, and convert them to the desired data types.

 n = int(input())  # Read an integer
 arr = list(map(int, input().split()))  # Read a list of integers

Fast I/O:

• In some competitive coding platforms, reading and writing to stdin/stdout can be slow. You can use sys.stdin.readline() for faster input reading and sys.stdout.write() for faster output.

 import sys

 n = int(sys.stdin.readline().strip())
 sys.stdout.write(f"{n}\n")

Use Built-in Functions:

• Python provides many built-in functions for common operations. Use functions like sorted(), max(), min(), sum(), and len() to simplify code.

Data Structures:

• Python has built-in data structures like lists, dictionaries, and sets that can be very useful. Familiarize yourself with their properties and methods.

List Comprehensions:

• List comprehensions allow you to create lists in a concise way. They are especially useful for creating lists from existing data or applying operations to elements in a list.

 squares = [x**2 for x in range(1, 6)]  # [1, 4, 9, 16, 25]

Dictionaries for Counting:

• Use dictionaries to count occurrences of elements. This is particularly useful for solving problems related to frequency counting.

 freq = {}
 for item in data:
     freq[item] = freq.get(item, 0) + 1

Built-in Modules:

• Python’s standard library includes many modules that can be helpful in competitive coding, such as collections, math, heapq, and itertools. Be familiar with their functions and classes.

String Manipulation:

• Python provides powerful string manipulation methods. You can use slicing, split(), join(), and regular expressions for efficient string handling.

Optimize Loops:

• Minimize nested loops whenever possible. Nested loops can lead to higher time complexity.

Efficient Sorting:

• Use the sorted() function for sorting, and specify custom sorting criteria using the key argument.

 sorted_list = sorted(data, key=lambda x: (x[1], x[0]))  # Sort by second element, then by first element

Use Memoization and Dynamic Programming:

• For problems involving recursion, dynamic programming, or repetitive calculations, use memoization (caching) to store intermediate results and reduce redundant computations.

Practice and Learn Algorithms:

• Competitive coding often involves algorithmic challenges. Practice sorting, searching, graph algorithms, and dynamic programming to improve your problem-solving skills.

Online Judges and Contests:

• Participate in online coding platforms like Codeforces, LeetCode, HackerRank, and TopCoder to practice and compete with others.

Test Cases and Edge Cases:

• Test your code with various test cases, including edge cases and boundary cases, to ensure correctness.

Code Reusability:

• Organize your code into functions and classes for reusability. This can save time in solving similar problems.

Read Others’ Solutions:

• After solving a problem, read and understand others’ solutions. This can help you learn different approaches and techniques.

Stay Calm and Manage Time:

• Competitive coding contests are time-bound. Stay calm, manage your time efficiently, and move on to the next problem if you get stuck.

Use Libraries Sparingly:

• While Python’s standard libraries are helpful, in some cases, you may need to implement algorithms or data structures yourself to optimize performance.

Practice Regularly:

• Consistent practice is key to improving your competitive coding skills. Set aside dedicated time for practice.

Learn from Mistakes:

• Analyze your mistakes and learn from them. Try to understand why a particular solution didn’t work and how you can improve.

Remember that competitive coding is about problem-solving, so focus on understanding the problem, devising an efficient solution, and implementing it effectively. Over time, practice and experience will lead to improved coding speed and accuracy.