Leet Code Problems

  Efficiently Calculating H-Index Using Binary Search in JavaScript Introduction The H-Index is a crucial metric used to measure the productivity and citation impact of a researcher’s published work. It provides a balanced view of both the quantity and quality of publications by considering the number of citations received. In this blog post, we will explore an efficient method to calculate the H-Index using binary search in JavaScript. Intuition To determine the H-Index, we need to find the largest number h such that there are at least h papers with at least h citations each. This means that for a given number of citations, we want to ensure that this number is at least as large as the number of papers that have received this many citations. Approach To efficiently calculate the H-Index, we can use the following steps: Sort the Citations : First, we sort the array of citations in ascending order. This will help us easily determine the number of papers with at least a certain nu...

  Efficiently Merging Two Sorted Arrays in JavaScript Introduction When working with arrays in JavaScript, a common task is to merge two sorted arrays into one sorted array. This challenge is frequently encountered in coding interviews and competitive programming. Today, we'll explore an efficient and elegant solution to this problem using a two-pointer technique. Problem Statement You are given two sorted integer arrays nums1 and nums2 , where nums1 has a size of m + n to accommodate the elements of nums2 at its end. Our goal is to merge these arrays into a single sorted array in place. Intuition The arrays are already sorted, so we can leverage this property to our advantage. By starting from the end of both arrays, we can efficiently place the largest elements at the end of nums1 , ensuring the array remains sorted. This approach minimizes the need for additional space and makes the merging process straightforward. Approach Initialize Pointers : i points to the last element...

  LeetCode Solution: Find the Middle of a Linked List in JavaScript Finding the middle node of a singly-linked list is a common problem on LeetCode. In this post, we will walk through the intuition, approach, and complexity of solving this problem using JavaScript. Below is the complete code solution, along with an explanation. Intuition To find the middle node of a linked list efficiently, we can use the two-pointer technique. By using two pointers, slow and fast , where slow moves one step at a time and fast moves two steps at a time, we can ensure that when fast reaches the end of the list, slow will be at the middle. This method allows us to determine the middle node in a single pass through the list. Approach Initialize Two Pointers : Initialize slow and fast pointers to the head of the linked list. Traverse the List : Use a while loop to move slow one step at a time and fast two steps at a time. Continue the loop until fast reaches the end of the list or fast.next ...

  Finding the Intersection Node in Two Linked Lists with JavaScript Finding the intersection node between two singly-linked lists is a classic problem that can be efficiently solved with a bit of clever maneuvering. In this blog post, we'll walk through the intuition, approach, and complexity analysis of finding the intersection node using JavaScript. We'll also include the complete code and a link to my detailed solution on LeetCode. Intuition The essence of solving this problem lies in the fact that the intersection point, if it exists, will be at the same distance from the end of both lists once they are aligned correctly. By calculating the lengths of both lists and aligning their starting points, we can simultaneously traverse the lists to find the intersection node. Approach Calculate the Lengths of Both Lists : First, we traverse both linked lists to determine their lengths. This helps in identifying the longer list and the difference in lengths between the two lists. Al...

  Finding the Longest Common Prefix in JavaScript When working with arrays of strings, a common problem is finding the longest common prefix among these strings. The longest common prefix is the initial portion of all strings in the array that is identical. This is a frequent problem on coding platforms like LeetCode, and it's essential to understand how to tackle it efficiently. In this blog post, we'll dive into the intuition, approach, and complexity of finding the longest common prefix in JavaScript. Intuition The intuition behind finding the longest common prefix is simple. By sorting the array of strings lexicographically (alphabetically), we can bring the smallest and largest strings to the beginning and end of the array. The common prefix between the first and last string in this sorted array will give us the longest common prefix for the entire array. This approach leverages the natural order of strings to simplify our task. Approach Sort the Array : First, we sort the...

  Finding the Greatest Common Divisor (GCD) in JavaScript When working with arrays of numbers, it's sometimes necessary to find the Greatest Common Divisor (GCD). The GCD of two or more integers is the largest positive integer that divides each of the integers without leaving a remainder. This concept is crucial in many areas, such as simplifying fractions, cryptography, and various algorithmic problems. In this blog post, we will explore a practical approach to finding the GCD of an array of numbers using JavaScript. We'll walk through the intuition, the approach, and the implementation, ending with a discussion on the complexity of the solution. Intuition The GCD of a set of numbers is a measure of the common factors shared among those numbers. To find the GCD of an array, one efficient approach is to consider only the maximum and minimum values of the array. This works because the GCD of the entire array is a divisor of the GCD of its maximum and minimum values. Approach Ide...

  Sorting Made Easy with a Custom sortBy Function in JavaScript Sorting arrays is a fundamental task in programming, and JavaScript provides powerful methods to accomplish this. However, there are times when you need to sort based on custom criteria. Let's dive into creating a custom sortBy function that allows for flexible and efficient sorting based on any criteria you define. Problem Statement We need a function sortBy that sorts an array based on a provided function. This function will take two arguments: arr (Array): The array to be sorted. fn (Function): The callback function that defines the sorting criterion. Code Implementation Here is the implementation of our custom sortBy function: javascript /** * @param {any[]} arr * @param {Function} fn * @return {any[]} */ var sortBy = function ( arr, fn ) { return arr. sort ( (a, b) => fn (a) - fn (b)); }; // Example Usage: // Sorting an array of numbers based on their values let numbers = [ 3 , 1 , 4 , 1 ,...

  Enhancing JavaScript Arrays with a Custom groupBy Method In the world of JavaScript, extending native prototypes can often make our code more efficient and readable. Today, I'm excited to share a method to group array elements based on a function you provide. This custom groupBy method is simple yet powerful, leveraging the capabilities of JavaScript's array methods. The Problem Grouping elements in an array is a common task in many applications. For example, given the array [1, 2, 3] and the grouping function String , we want the output to be: json { "1" : [ 1 ] , "2" : [ 2 ] , "3" : [ 3 ] } To achieve this, we will create a custom groupBy method that categorizes array elements efficiently. The Solution Here’s the code for our groupBy method: javascript /** * @param {Function} fn * @return {Object} */ Array . prototype . groupBy = function ( fn ) { return this . reduce ( (group, item) => { const key = fn (item); ...