Describe a challenging project you worked on. What were the prerequisites for success, and how did you overcome the challenges?

LeetCode #207 - Course Schedule\nYou are given an array of prerequisites where prerequisites[i] = [a, b] indicates that to take course a you must first take course b. Return true if you can finish all courses.\n\n**Input:**\nnumCourses = 2, prerequisites = [[1,0]]\n**Output:**\ntrue\n\n**Constraints:**\n1 <= numCourses <= 2000\n0 <= prerequisites.length <= 5000\nprerequisites[i].length == 2\nAll prerequisite pairs are unique.

How would you design a URL shortening service like bit.ly? What are the key components, and how would you handle scaling?