Given the root of a binary tree, return the length of the longest path, where each node in the path has the same value. This path may or may not pass through the root. The length of the path between two nodes is represented by the number of edges between them. Example 1: Input: root = [5,4,5,1,1,null,5] Output: 2 Explanation: The shown image shows that the longest path of the same value (i.e. 5)..

Given the root of a binary tree, return the length of the diameter of the tree. The diameter of a binary tree is the length of the longest path between any two nodes in a tree. This path may or may not pass through the root. The length of a path between two nodes is represented by the number of edges between them. Example 1: Input: root = [1,2,3,4,5] Output: 3 Explanation: 3 is the length of the..

Given the root of a binary tree, return its maximum depth. A binary tree's maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node. Example 1: Input: root = [3,9,20,null,null,15,7] Output: 3 Example 2: Input: root = [1,null,2] Output: 2 Constraints: The number of nodes in the tree is in the range [0, 104]. -100

There are n cities connected by some number of flights. You are given an array flights where flights[i] = [fromi, toi, pricei] indicates that there is a flight from city fromi to city toi with cost pricei. You are also given three integers src, dst, and k, return the cheapest price from src to dst with at most k stops. If there is no such route, return -1. Example 1: Input: n = 4, flights = [[0,..

You are given a network of n nodes, labeled from 1 to n. You are also given times, a list of travel times as directed edges times[i] = (ui, vi, wi), where ui is the source node, vi is the target node, and wi is the time it takes for a signal to travel from source to target. We will send a signal from a given node k. Return the minimum time it takes for all the n nodes to receive the signal. If i..

class Solution(object): def canFinish(self, numCourses, prerequisites): """ :type numCourses: int :type prerequisites: List[List[int]] :rtype: bool """ graph = collections.defaultdict(list) # 그래프 구성 for x, y in prerequisites: graph[x].append(y) traced = set() visited = set() def dfs(i): # 순환 구조이면 False if i in traced: return False # 이미 방문했던 노드이면 True if i in visited: return True traced.add(i) fo..