Blog Posts

a collection of coding articles

  • The Algorithm Series: Check Completeness of a Binary Tree

    Given the root of a binary tree, determine if it is a complete binary tree. In a complete binary tree, every level, except possibly the last, is completely filled, and all nodes in the last level are as far left as possible. It can have between 1 and 2h nodes inclusive at the last level h.

  • The Algorithm Series: Check If It Is a Straight Line

    You are given an array coordinates, coordinates[i] = [x, y], where [x, y] represents the coordinate of a point. Check if these points make a straight line in the XY plane.

  • The Algorithm Series: Capacity To Ship Packages Within D Days

    Explaining how to solve algorithm tasks (via Leetcode).

    A conveyor belt has packages that must be shipped from one port to another within days days. The ith package on the conveyor belt has a weight of weights[i]. Each day, we load the ship with packages on the conveyor belt (in the order given by weights). We may not load more weight than the maximum weight capacity of the ship. Return the least weight capacity of the ship that will result in all the packages on the conveyor belt being shipped within days days.

  • The Algorithm Series: Can Make Arithmetic Progression From Sequence

    Explaining how to solve algorithm tasks (via Leetcode).

    A sequence of numbers is called an arithmetic progression if the difference between any two consecutive elements is the same. Given an array of numbers arr, return true if the array can be rearranged to form an arithmetic progression. Otherwise, return false.

  • The Algorithm Series: Can Place Flowers

    Explaining how to solve algorithm tasks (via Leetcode).

    You have a long flowerbed in which some of the plots are planted, and some are not. However, flowers cannot be planted in adjacent plots. Given an integer array flowerbed containing 0`s and 1`s, where 0 means empty and 1 means not empty, and an integer n, return if n new flowers can be planted in the flowerbed without violating the no-adjacent-flowers rule.

  • The Algorithm Series: Checking Existence of Edge Length Limited Paths

    An undirected graph of n nodes is defined by edgeList, where edgeList[i] = [ui, vi, disi] denotes an edge between nodes ui and vi with distance disi. Note that there may be multiple edges between two nodes. Given an array queries, where queries[j] = [pj, qj, limitj], your task is to determine for each queries[j] whether there is a path between pj and qj such that each edge on the path has a distance strictly less than limitj.

  • The Algorithm Series: Bulb Switcher

    There are n bulbs that are initially off. You first turn on all the bulbs, then you turn off every second bulb. On the third round, you toggle every third bulb (turning on if it`s off or turning off if it`s on). For the ith round, you toggle every i bulb. For the nth round, you only toggle the last bulb. Return the number of bulbs that are on after n rounds.

  • The Algorithm Series: Task Boats to Save People

    You are given an array people where people[i] is the weight of the ith person, and an infinite number of boats where each boat can carry a maximum weight of limit. Each boat carries at most two people at the same time, provided the sum of the weight of those people is at most limit. Return the minimum number of boats to carry every given person.

  • The Algorithm Series: Binary Tree Zigzag Level Order Traversal

    Given the root of a binary tree, return the zigzag level order traversal of its nodes` values. (i.e., from left to right, then right to left for the next level and alternate between).

  • The Algorithm Series: Best Time to Buy and Sell Stock

    Explaining how to solve algorithm tasks (via Leetcode).

    You are given an array prices where prices[i] is the price of a given stock on the ith day. You want to maximize your profit by choosing a single day to buy one stock and choosing a different day in the future to sell that stock. Return the maximum profit you can achieve from this transaction. If you cannot achieve any profit, return 0.

  • The Algorithm Series: Average Salary Excluding the Minimum and Maximum Salary

    Explaining how to solve algorithm tasks (via Leetcode).

    You are given an array of unique integers salary where salary[i] is the salary of the ith employee. Return the average salary of employees excluding the minimum and maximum salary. Answers within 10-5 of the actual answer will be accepted.

  • The Algorithm Series: As Far from Land as Possible

    Given an n x n grid containing only values 0 and 1, where 0 represents water and 1 represents land, find a water cell such that its distance to the nearest land cell is maximized, and return the distance. If no land or water exists in the grid, return -1. The distance used in this problem is the Manhattan distance: the distance between two cells (x0, y0) and (x1, y1) is |x0 - x1| + |y0 - y1|.

  • The Algorithm Series: Find All Anagrams in a String

    Given two strings s and p, return an array of all the start indices of p`s anagrams in s. An Anagram is a word or phrase formed by rearranging the letters of a different word or phrase, typically using all the original letters exactly once.

  • The Algorithm Series: Verifying an Alien Dictionary

    Explaining how to solve algorithm tasks (via Leetcode).

    In an alien language, surprisingly, they also use English lowercase letters, but possibly in a different order. The order of the alphabet is some permutation of lowercase letters. Given a sequence of words written in the alien language, and the order of the alphabet, return true if and only if the given words are sorted lexicographically in this alien language.

  • The Algorithm Series: Add to Array-Form of Integer

    Explaining how to solve algorithm tasks (via Leetcode).

    The array-form of an integer num is an array repanswerenting its digits in left to right order. For example, for num = 1321, the array form is [1,3,2,1]. Given num, the array-form of an integer, and an integer k, return the array-form of the integer num + k.

  • The Algorithm Series: Add Digits

    Explaining how to solve algorithm tasks (via Leetcode).

    Given an integer num, repeatedly add all its digits until the result has only one digit, and return it.

  • The Algorithm Series: Add Binary

    Explaining how to solve algorithm tasks (via Leetcode).

    Given two binary strings a and b, return their sum as a binary string.