DSA

What is a Stack? A stack is an abstract data type that serves as a collection of elements and implements operations like push, pop, and peek at the end in O(1) time. It uses the LIFO (last in, first out) order. For example, a stack can be a collection of items where adding or removing is practical at the top. Code Example struct Stack<Element> { private var array: [Element] init(array: [Element] = []) { self.array = array } mutating func push(_ element: Element) { array.append(element) } mutating func pop() -> Element? { if array.isEmpty { return nil } return array.popLast() } func peek() -> Element? { if array.isEmpty { return nil } return array.last } } Practical Applications of Stacks You can observe stack-like behavior in many places, such as redo-undo features in text editors, Photoshop, and the forward and backward navigation features in web browsers. ...

What is the Two Pointers Technique? The two pointers technique helps track indices in a collection of elements to access objects in memory by index with O(1) space. This technique is very handy when you need to optimize the time and space of a solution. What Problems Does It Solve? The two pointers technique solves problems involving collections. For example, it is useful when you need to compare each element to other elements in that collection. ...

Introduction In the previous chapter, we discussed Data Structures and Algorithms, delved into an overview of Dynamic Arrays, and solved the “Remove Element” problem. In this article, I’m going to show one of the ways to solve the 88. Merge Sorted Array problem. Problem You are given two integer arrays, nums1 and nums2, sorted in non-decreasing order, and two integers, m and n, representing the number of elements in nums1 and nums2, respectively. Merge nums1 and nums2 into a single array sorted in non-decreasing order. The final sorted array should not be returned by the function but should instead be stored inside the array nums1. To accommodate this, nums1 has a length of m + n, where the first m elements denote the elements that should be merged, and the last n elements are set to 0 and should be ignored. nums2 has a length of n. ...

Introduction I’ve always been curious about data structures and algorithms, and how they can improve user experiences while saving money for businesses through optimized computations. In this series of articles, I’m going to solve LeetCode problems and share my approach with you. I’ve just started my journey in solving LeetCode problems, so my solutions might not be as efficient as they could be, but I’m always looking for improvement. Before each topic, I’ll provide a brief introduction to the data structure, algorithm, or technique I’ll be using to solve a specific problem. ...