Code-Alongs
Code-Along 1: Introduction to LeetCode and Basic Data Types
In this code-along, you'll learn how to navigate LeetCode and work with basic data types in JavaScript.
Repository Links
Code-Along 2: Problem Solving with JavaScript
Join us for a live coding session where we'll solve various programming problems using JavaScript.
Problem-Solving Approaches and Patterns
Developing a systematic approach to problem-solving is crucial for tackling coding challenges. Here's a framework to help you approach any coding problem:
The UMPIRE Method
- Understand the problem - Read carefully, identify inputs/outputs, clarify constraints
- Match the problem to similar ones - Recognize patterns from problems you've seen before
- Plan your approach - Design an algorithm before coding
- Implement your solution - Convert your plan to code
- Review your code - Look for bugs, edge cases, or optimizations
- Evaluate your solution - Analyze time and space complexity
Common Problem Types and Approaches
1. String Manipulation Problems
Example: Valid Palindrome
Problem: Determine if a string is a palindrome, considering only alphanumeric characters and ignoring case.
Approach:
- Remove non-alphanumeric characters and convert to lowercase
- Compare the string with its reverse
function isPalindrome(s) {
// Remove non-alphanumeric and convert to lowercase
const cleanString = s.toLowerCase().replace(/[^a-z0-9]/g, '');
// Check if it reads the same forward and backward
return cleanString === cleanString.split('').reverse().join('');
}
console.log(isPalindrome("A man, a plan, a canal: Panama")); // true
console.log(isPalindrome("race a car")); // false2. Array Problems
Example: Two Sum
Problem: Given an array of numbers and a target sum, find two numbers that add up to the target.
Approach:
- Naive: Use nested loops to check all pairs (O(n²) time)
- Optimal: Use a hash map to store differences (O(n) time)
function twoSum(nums, target) {
// Create a map to store values we've seen and their indices
const map = new Map();
// Check each number
for (let i = 0; i < nums.length; i++) {
// Calculate what value we need to find
const complement = target - nums[i];
// If we've seen that value before, return its index and the current index
if (map.has(complement)) {
return [map.get(complement), i];
}
// Otherwise, store this number and its index
map.set(nums[i], i);
}
return null; // No solution found
}
console.log(twoSum([2, 7, 11, 15], 9)); // [0, 1]