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Articles by Sarika Singh
Page 2 of 14
__exit__ in Python
In Python, some special methods have names that start and end with double underscores. These are called dunder methods. One such method is __exit__, which is used in context managers for cleanup tasks. Context Manager in Python Context Mangers helps to manage resources such as files, database connections, or network links. It sets up a temporary environment to run a block of code. When the block ends, Python closes the file or disconnects the connection automatically. This prevents unnecessary resource consumption when we leave a file open or keep a connection (such as, network, database) active. Python runs context managers ...
Read More__name__ (A Special variable) in Python
Python does not require a main function to start execution like many other programming languages. Instead, it uses a special built-in variable called __name__ to determine how a Python script is being executed (directly or, is it imported as a module into another script). In this article, we will learn about the __name__ variable in Python. Understanding the __name__ Variable The __name__ variable is a built-in variable that holds the name of the current module. When you run a script directly, Python sets __name__ to __main__. If the same script is imported into another file as a module, __name__ ...
Read More__future__ Module in Python
What is the __future__ Module? The __future__ is a built-in Python module that is used to import features from newer versions of Python into older versions. This helps you to write code that will work the same way in both old and new versions of Python. It is mainly used when you are migrating code from Python 2 to Python 3, or when you want to try out new features before they become standard (default) in future releases. For example, in older Python versions, dividing two integers would return an integer. But if you import the division feature like this: ...
Read MorePython Program for Detect Cycle in a Directed Graph
A cycle occurs when a path starts and ends at the same vertex, following the direction of the edges. In directed graphs, cycles can cause problems like infinite loops or dependency errors, so detecting them is important in areas like task scheduling and deadlock detection. We can use Depth-First Search (DFS) with a recursion stack to detect whether a cycle exists in a directed graph or not. Problem Statement You are given a directed graph represented using an adjacency list. Your task is to write a Python program to check whether the graph contains a cycle or not. DFS-Based Cycle ...
Read MorePython Program for Cutting a Rod
Rod Cutting ProblemThe Rod Cutting problem is a classic example of dynamic programming. The goal is to cut a rod into pieces to maximize the total value. Each piece has a specific length and value, and we must choose the cuts in such a way that the total value is as high as possible. This problem is similar to the 0-1 Knapsack problem and can be solved using recursion and dynamic programming techniques. It is useful in resource allocation and pricing strategies. Rod Cutting Problem Statement You are given a rod of length n and an array price[] where price[i] ...
Read MorePython Program for Cocktail Sort
What is Cocktail Sort? Cocktail sort is a variation of bubble sort that sorts the array in both directions on each pass. It is also known as Bidirectional Bubble Sort or Shaker Sort. The algorithm works by traversing the list forward and backward, alternatively, pushing the largest and smallest elements to their respective ends. This approach helps in reducing the number of iterations compared to Bubble Sort, especially when smaller elements are at the end of the list. Problem Statement You are given an unsorted list of elements. The goal is to sort the list using Cocktail Sort, which moves ...
Read MorePython Program for BogoSort or Permutation Sort
BogoSort, also known as Permutation Sort or Stupid Sort, is a sorting algorithm based on generating random permutations of the list until it gets sorted. BogoSort continues to shuffle the array randomly until the list becomes sorted. The expected time complexity is unbounded, and its average performance is extremely poor. Problem Statement You are given a list of unsorted elements. Your task is to sort the list using BogoSort by repeatedly generating random permutations until the list is sorted. Random Permutation-based Sorting This sorting method checks if the list is sorted. If not, it randomly shuffles the elements and checks ...
Read MorePython Program for Binary Insertion Sort
Binary Insertion SortBinary insertion sort is an improved version of the regular Insertion Sort algorithm. In a normal insertion sort, each element is compared linearly with the sorted portion of the list to find its correct position. This takes O(n) comparisons for each element. In Binary Insertion Sort, we use Binary Search to find the correct position of the current element in the sorted part of the list. This reduces the number of comparisons from O(n) to O(log n) per insertion. However, shifting elements still takes O(n) time in the worst case. Problem Statement You are given a list of ...
Read MorePython Program for Activity Selection Problem
The activity selection problem selects the maximum number of non-overlapping activities from a given set. Each activity has a start and finish time, and a single person can perform only one activity at a time. Problem Statement You are given n activities, each defined by a start time and a finish time. The goal is to choose the maximum number of activities that a single person can perform without any overlap between the selected activities. Variable Notations Below are the variables used in the problem definition: N: Total number of activities S: ...
Read MoreHow to remove all leading whitespace in string in Python?
Leading whitespace refers to any spaces, tabs, or other blank characters that appear at the start of a string. These characters come before the first visible text and can affect how the string is displayed. We can remove all leading whitespace from a string in Python using the lstrip() function. Using the lstrip() Function The lstrip() function removes all whitespace characters from the beginning (left side) of a string (leading whitespace). It does not affect any whitespace at the end or in the middle of the string. There are also two related functions i.e. rstrip() and strip() - ...
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