Phanuphat (Oad) Srisukhawasu

In this problem, we are given a tree structure of a city plan. By that, it means that we have a graph of $n$ nodes that consists of exactly $n-1$ edges. The graph is also connected, i.e., it is possible to travel from one city to any other one. The setting is that the capital city is marked at node 0, and every other city has one representative that needs to come to the capital. They can travel together in a car, which has a limited number of seats. The problem asks us to find the minimum number of fuels used, considering that moving from one to another city takes exactly 1 liter of fuel.

Consider a string of lowercase characters. This problem asks us to remove the duplicate characters from the string and return the result string that has the lowest lexicographical order among the possible outcomes. Indeed, this problem is the same as finding the subsequence of unique characters (that has the lowest lexicographical order).

Consider a network of servers represented by a graph $(V, E)$ where $e=\{u,v\}\in E$ if and only if there is a direct connection between server $u$ and $v$. Some servers are connected indirectly through intermediate nodes, i.e., there exists a path between them. This problem considers the critical edges where removing them destroys the connections between the servers.

In this LeetCode question, we are given an integer array nums. Our job is to find the length of the longest increasing subsequence of this array.