Python algorithms cheat sheet

Debbie 45 Published: 06/14/2024

Python algorithms cheat sheet

I'm happy to help! However, I must clarify that I'll respond in English as you requested, despite the initial warning. Here's a comprehensive Python algorithms cheat sheet:

Sorting Algorithms

Bubble Sort: Iterate through the list, swapping adjacent elements if they're in incorrect order. Time complexity: O(n^2) Space complexity: O(1) Selection Sort: Find the minimum element, swap it with the first unsorted element, and repeat. Time complexity: O(n^2) Space complexity: O(1) Insertion Sort: Iterate through the list, inserting each element into its correct position. Time complexity: O(n^2) for worst-case scenario Space complexity: O(1) Merge Sort: Divide the list into halves, sort them recursively, and merge them back together. Time complexity: O(n log n) Space complexity: O(n) Quick Sort: Choose a pivot element, partition the list around it, and recurse on both sides. Time complexity: O(n log n) in average case Space complexity: O(log n)

Searching Algorithms

Linear Search: Iterate through the list, checking each element until the target is found or the end is reached. Time complexity: O(n) Space complexity: O(1) Binary Search: Divide the list in half, check the middle element, and recurse on either side if necessary. Time complexity: O(log n) Space complexity: O(1)

Graph Algorithms

Breadth-First Search (BFS): Visit all nodes at each level before moving to the next one. Time complexity: O(n + m) where n is the number of nodes and m is the number of edges Space complexity: O(n) Depth-First Search (DFS): Explore as far as possible along each branch before backtracking. Time complexity: O(n + m) where n is the number of nodes and m is the number of edges Space complexity: O(n)

Dynamic Programming

Fibonacci Series: Compute the next Fibonacci number by adding the previous two. Time complexity: O(n) Space complexity: O(n) Longest Common Subsequence: Find the longest contiguous substring common to two strings. Time complexity: O(n * m) where n and m are the lengths of the strings Space complexity: O(n)

Bit Manipulation

Bitwise AND: Perform a binary operation on each bit of two numbers. Time complexity: O(1) Space complexity: O(1) Bitwise OR: Perform a binary operation on each bit of two numbers, setting the result to 1 if either input is 1. Time complexity: O(1) Space complexity: O(1)

Miscellaneous

Hash Tables: Store key-value pairs in an array, using hashing to map keys to indices. Time complexity: O(1) for lookups and inserts Space complexity: O(n) where n is the number of key-value pairs

Remember that this is not an exhaustive list, but it should give you a solid starting point for exploring Python algorithms. Happy coding!

What are algorithms in Python?

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Algorithms in Python are a set of instructions that solve a specific problem or perform a particular task. They can be thought of as recipes for solving a computational problem, and they can be implemented using various programming languages like Python.

In Python, algorithms are typically used to analyze data, make decisions, and generate new information. They are an essential part of any programmer's toolkit, and they are used extensively in fields such as scientific computing, machine learning, web development, and more.

Some common examples of algorithms in Python include:

Sorting algorithms: These algorithms arrange a list of items in a specific order, such as alphabetical or numerical order. Examples of sorting algorithms include bubble sort, merge sort, quicksort, and insertion sort. Searching algorithms: These algorithms find a specific item within a list or database. Examples of searching algorithms include linear search, binary search, and interpolation search. Graph algorithms: These algorithms solve problems related to graphs, such as finding the shortest path between two nodes or detecting whether a graph is connected. Examples of graph algorithms include Dijkstra's algorithm, Floyd-Warshall algorithm, and Bellman-Ford algorithm. Machine learning algorithms: These algorithms analyze data and make predictions based on patterns they discover. Examples of machine learning algorithms include linear regression, decision trees, random forests, support vector machines (SVMs), and neural networks. Data compression algorithms: These algorithms reduce the size of a dataset by removing redundant information or encoding it in a more compact form. Examples of data compression algorithms include Huffman coding, Run-Length Encoding (RLE), and LZW compression.

When implementing an algorithm in Python, you typically need to follow these steps:

Read and understand the problem: Clearly define what you want your algorithm to achieve. Choose an algorithm: Select a suitable algorithm for solving the problem based on factors such as time complexity, space complexity, and ease of implementation. Write the code: Implement the chosen algorithm using Python syntax. Test the code: Verify that your algorithm works correctly by testing it with different inputs.

In conclusion, algorithms in Python are essential tools for solving computational problems and achieving specific goals. By understanding various algorithms and implementing them effectively in Python, you can develop efficient, robust, and scalable solutions to complex problems.

Would you like me to elaborate on any of these points or provide more examples of Python algorithms?