Marcy Blog

Failed to be a geek

Problem: Making A Large Island

Question In a 2D grid of 0s and 1s, we change at most one 0 to a 1. After, what is the size of the largest island? (An island is a 4-directionally connected group of 1s). Example 1: Input: [[1, ...

Problem: Number of Islands

Question Given a 2d grid map of '1's (land) and '0's (water), count the number of islands. An island is surrounded by water and is formed by connecting adjacent lands horizontally or vertically. Y...

Problem: Course Schedule II

Question There are a total of n courses you have to take, labeled from 0 to n-1. Some courses may have prerequisites, for example to take course 0 you have to first take course 1, which is expres...

Problem: Alien Dictionary

Question There is a new alien language which uses the latin alphabet. However, the order among letters are unknown to you. You receive a list of non-empty words from the dictionary, where words ar...

Problem: Minimum Height Trees

Question For a undirected graph with tree characteristics, we can choose any node as the root. The result graph is then a rooted tree. Among all possible rooted trees, those with minimum height ar...

Problem: Shortest Distance from All Buildings

Question You want to build a house on an empty land which reaches all buildings in the shortest amount of distance. You can only move up, down, left and right. You are given a 2D grid of values 0,...

Problem: Network Delay Time

Question There are N network nodes, labelled 1 to N. Given times, a list of travel times as directed edges times[i] = (u, v, w), where u is the source node, v is the target node, and w is the tim...

Problem: Jump Game II

Question Given an array of non-negative integers, you are initially positioned at the first index of the array. Each element in the array represents your maximum jump length at that position. Yo...

Problem: Snakes and Ladders

Question On an N x N board, the numbers from 1 to N*N are written boustrophedonically starting from the bottom left of the board, and alternating direction each row. For example, for a 6 x 6 boar...

Problem: Binary Tree Vertical Order Traversal

Question Given a binary tree, return the vertical order traversal of its nodes’ values. (ie, from top to bottom, column by column). If two nodes are in the same row and column, the order should b...