Leetcode 281: Zigzag Iterator
Given two 1d vectors, implement an iterator to return their elements alternately.
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Leetcode 280: Wiggle Sort
Question Given an unsorted array nums, reorder it in-place such that nums[0] <= nums[1] >= nums[2] <= nums[3].... [Read More] -
Leetcode 279: Perfect Squares
Question Given a positive integer n, find the least number of perfect square numbers (for example, 1, 4, 9, 16, ...) which sum to n. [Read More] -
Leetcode 278: First Bad Version
Question You are a product manager and currently leading a team to develop a new product. Unfortunately, the latest version of your product fails the quality check. Since each version is developed based on the previous version, all the versions after a bad version are also bad. [Read More] -
Leetcode 277: Find the Celebrity
Question Suppose you are at a party with n people (labeled from 0 to n - 1) and among them, there may exist one celebrity. The definition of a celebrity is that all the other n - 1 people know him/her but he/she does not know any of them. [Read More] -
Leetcode 276: Paint Fence
Question There is a fence with n posts, each post can be painted with one of the k colors. [Read More] -
Leetcode 272: Closest Binary Search Tree Value II
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Breath-First Search
Breadth-first search (BFS) is an algorithm for traversing or searching tree or graph data structures. It starts at the tree root (or some arbitrary node of a graph), and explores all of the neighbor nodes at the present depth prior to moving on to the nodes at the next depth... [Read More] -
Leetcode 207: Course Schedule
Question There are a total of n courses you have to take, labeled from 0 to n-1. [Read More] -
Leetcode 210: Course Schedule II
Question There are a total of n courses you have to take, labeled from 0 to n-1. [Read More] -
Topological Sorting
Topological sorting for Directed Acyclic Graph (DAG) is a linear ordering of vertices such that for every directed edge (u, v), vertex u comes before v in the ordering. Topological Sorting for a graph is not possible if the graph is not a DAG. The first vertex in topological sorting... [Read More] -
Depth First Search
Depth First Traversal (or Search) for a graph is similar to Depth First Traversal of a tree. The only catch here is, unlike trees, graphs may contain cycles, so we may come to the same node again. To avoid processing a node more than once, we use a boolean visited... [Read More] -
Leetcode 68: Text Justification
Question Given an array of words and a width maxWidth, format the text such that each line has exactly maxWidth characters and is fully (left and right) justified. [Read More] -
Leetcode 57: Insert Interval
Question Given a set of non-overlapping intervals, insert a new interval into the intervals (merge if necessary). [Read More] -
Leetcode 271: Encode and Decode Strings
Question Design an algorithm to encode a list of strings to a string. The encoded string is then sent over the network and is decoded back to the original list of strings. [Read More]