Author: admin
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Harvard CS50’s Artificial Intelligence with Python Day1: Search
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Search Algorithms (搜索算法) Definition (定义): Search algorithms are used to find solutions by exploring different states or configurations of a problem. They are fundamental in areas such as pathfinding, game playing, and puzzle solving. 搜索算法用于通过探索问题的不同状态或配置来寻找解决方案。它们在路径查找、游戏和拼图解决等领域中是基础。 Types of Search Algorithms (搜索算法的类型): Uninformed Search (无信息搜索，盲目搜索): Breadth-First Search (BFS) (广度优先搜索): Explores all nodes…
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LeetCode: 226 Invert Binary Tree
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Invert a binary tree. Example: Input: 4 / \ 2 7 / \ / \ 1 3 6 9 Output: 4 / \ 7 2 / \ / \ 9 6 3 1 问题 翻转一棵二叉树。 解决方案 1 递归方法 Approach 1 / 方法 1 This solution uses a recursive approach. The…
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LeetCode: 110 Balanced Binary Tree
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Given a binary tree, determine if it is height-balanced. For this problem, a height-balanced binary tree is defined as: A binary tree in which the left and right subtrees of every node differ in height by no more than 1. Example: Input: root = [3,9,20,null,null,15,7] Output: true Input: root =…
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Python 101: Exploring the Efficiency and Implementation of Python’s `enumerate()` Function
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The enumerate() function in Python is a built-in function that adds a counter to an iterable and returns it in the form of an enumerate object. This function is highly useful when you need to loop through an iterable and keep track of the index of each item. How enumerate()…
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Python 101: Understanding the Python `range()` Function
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The range() function in Python generates a sequence of numbers. It’s commonly used for looping a specific number of times in for loops. While the range() function appears straightforward, its implementation is a bit more complex. Here’s a detailed look at how the range() function is implemented and how it…
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Python 101: Understanding the Implementation of Python’s `match` Function
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Python’s match function is part of the re module, which provides support for regular expressions. The match function checks for a match only at the beginning of the string, while search checks for a match anywhere in the string. Here is a simplified explanation of how the match function works,…
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Python 101: Understanding the Implementation of Python’s `isalnum()` Method in Detail
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The isalnum() method in Python is used to check if all characters in a string are alphanumeric. Alphanumeric characters are those that consist of letters and numbers. In Python, the isalnum() method is implemented in C within the CPython source code for performance reasons. While we can’t directly see the…
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LeetCode: 125 Valid Palindrome
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Given a string s, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases. Example: Input: "A man, a plan, a canal: Panama" Output: true Input: "race a car" Output: false 问题 给定一个字符串 s，判断它是否是一个回文字符串，仅考虑字母数字字符并忽略大小写。 解决方案 1 双指针法 Approach 1 / 方法 1 使用双指针从字符串的两端向中间移动，忽略非字母数字字符，并比较字母数字字符是否相等。 Detailed Steps / 详细步骤…
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LeetCode: 242. Valid Anagram
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Given two strings s and t, return true if t is an anagram of s, and false otherwise. Example: Input: s = "anagram", t = "nagaram" Output: true Input: s = "rat", t = "car" Output: false 问题 给定两个字符串 s 和 t，如果 t 是 s 的字母异位词，则返回 true，否则返回 false。 解决方案 1…
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Python 101: Unpacking Python’s Counter Class with A Detailed Look at Its Source Code and Functionality
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The Counter class in Python’s collections module is implemented in C for performance reasons. However, a simplified version in Python can help us understand its functionality and structure. Below is a detailed explanation of a basic version of Counter. Simplified Source Code for Counter from collections import defaultdict class Counter(dict):…