LeetCode

The Problem Given an integer array nums, return true if any value appears at least twice in the array, and return false if every element is distinct. Example Input: nums = [1,2,3,1] Output: true Explanation: The element 1 occurs at indices 0 and 3. Follow-up: Can you come up with an algorithm that has less than O(NlogN) time complexity? Brute Force Solution func containsDuplicate(_ nums: [Int]) -> Bool { var nums = nums let N = nums.count if N == 0 { return false } nums.sort() var prev = nums[0] for i in 1 ..< N { let num = nums[i] if num == prev { return true } else { prev = num } } return false } Explanation The brute force solution for this problem uses sorting to allow us to quickly detect duplicates since identical elements will be adjacent. After sorting, it iterates through all elements, checking if the current element is equal to the previous one; if it is, it returns true immediately. If not, it updates prev. If no duplicates are detected, it returns false. ...

The Problem Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to the target. You may assume that each input would have exactly one solution, and you may not use the same element twice. You can return the answer in any order. Example Input: nums = [2,7,11,15], target = 9 Output: [0,1] Explanation: Because nums[0] + nums[1] == 9, we return [0, 1]. Follow-up: Can you come up with an algorithm that has less than O(N^2) time complexity? ...

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. ...